s2fieldsofstudy: Education Linguistics

text:
Characteristics of Pronoun “Who and Its Concordance” in Chinese College Students’ English Narrative Writing from the Perspective of Corpus-Based Method-A Case Study of Series of Compositions of “The Most Unforgettable Person I Ever Know”

Writing is one of productive skills and a way of conveying information considered to be the most complex and the most challenging skill for EFL English learners to acquire, hence many studies have been conducted on the revelation of the characteristic of writings of EFL learners and how to improve them. Among them, pronoun study has attracted extensive interest and become a hot spot in the second language acquisition and contrastive linguistics. Taking a series of compositions of “The most unforgettable person I ever know” as subject, this study is devoted to reveal the characteristics of “who and its concordance” in Chinese college students` English narrative writing from the perspective of corpus-based method. Result of contrastive analysis of writing from 630 college students of 3 colleges in the past 6 years shows: 1) As a whole, WIC can be regarded as common words for Chinese college students but the distribution of individual word is relatively disproportionate-“who” attracts far more attention while the other 4 words attract little or no attention. 2) In terms of sentence type, the distribution of the 5 types is imbalance with too little use of adverbial clause and too much of attributive clauses. In addition, the learners are used to utilizing simple and identical sentence structure and some of them are highly repetitive. 3) The use frequency of WIC of individual student shows that the majority numbers of learners have formed the habit of using them to depict interpersonal relationship and their distribution is unbalanced too. 4) As to the clusters, the learners have formed the habit of preference use of “who” as a relative pronoun above all. And some clusters are highly identical and simple. 5) To sum up, the majority of learners in this study can employ WIC consciously in their writing, but their usages are confined to simple words and structures. Therefore, the learner`s comprehensive competence of integrated employment of WIC should be improved.

and Internet technology has enabled linguists to analyses a vast amount of learners` authentic language data. And the Corpus-based methodology is able to export objective and convincing research findings after undergoing scientific statistic analysis procedure. Therefore, with the availability of the text of learner corpora, SLA researchers are beginning to focus on descriptive aspects of interlanguage processes and to discover in more detail the use/misuse of language features and their frequencies and distribution at different developmental stages (Li, 2017). Until now, considerable achievements have been attained in both corpus construction and corpus-based research of language. Moreover, methods adopted in the corpus linguistics have been applied to almost all the fields of linguistics.

Why Choose Pronoun
As a very important part of speech in English, pronoun is a kind of substitutive words that are used frequently in English language because it can avoid redundancy of antecedents and make discourse more compact and perspicuous. They are of great importance to the cohesion of the discourse, to the clear expression of meanings and to the establishment and maintaining of interpersonal relationships. It exerts a great influence in 3 aspects which are the expression of communication, the demonstration of interpersonal meaning and the cohesion of text. Pronouns may seem easy to learn in the surface but are hard to deal with due to their enormous usage as well as complicated linkages to various sentence patterns. Therefore, in recent years, a great number of researchers and scholars have done a lot of studies about English pronouns, demonstrating how pronouns are used from different aspects both in language teaching and learning (Li, 2012).

What is Pronoun "Who and Its Concordance"
In this study, "who and its concordance (WIC)" refer to "who" and its derivations, that is to say, WIC is composed of 5 words: who, whom, whose, whoever, and whomever. These words can either serve as interrogative pronouns in independent clause as sample 1 or as conjunctive pronouns in dependent clause as sample 2 or as relative pronouns in dependent clause as sample 3. Based on the sentence components that WIC play, the researcher classifies their usage into 5 types and 8 subtypes as the following examples shown in table 1. Among them the "Role in higher matrix clause" refers to the role that WIC and its antecedent plays in higher matrix clause in the attributive clause. Object God helps those who help themselves.

Predicative
Happy is the man who is contented with his lot.
There are those who eat out for a special occasion, or treat themselves.
Non-restrictive Subject Mrs. Smith, who has a lot of teaching experience at junior level, will be joining the school in September.

Object
He was accompanied by Winston Churchill, who is the Britain`s prime minister during the Second World War.
We were worried about our nearest neighbors, who were newcomers to the district.
Predicative This is Mrs. Smith, who has a lot of teaching experience at junior level.

Appositive
Winston Churchill, who is the Britain`s prime minister during the Second World War, died in 1965.
Nominal clause Subject It was uncertain who was responsible for the accident.
Who goes light travels fast.

Object
Can you tell me who is responsible for the accident?
You must give it back to who/ whoever it belongs to.

Predicative
The problem is not who will go but who will stay.

Research Outside China
From the perspective of acquisition, Butterworth and Hatch (1978) explore French EFL learners' acquisition of English genitive pronouns, while Felix and Hahn (1985) explore various forms of third personal pronouns in terms of gender for German learners. Ellis (1994:96) finds out that second language learners are challenged by the complicated system of English personal pronouns. Chan and Wong (2001) find that Malaysian has no distinction in gender on third person singular pronouns. Harris and Bates (2002), Wolf and Gibson (2004) test the pronominal reference or the processing preferences for English pronouns.
From the perspective of semantic analysis, YURIKO ASHIMA-TAKANE (1991) indicates that the child persistently made pronominal errors due to semantic confusion after the clear comprehension and production. Stevenson, Knott, and Oberlander (2000:225) concentrate on "the relationship between focusing and coherence relations in pronoun interpretation". Chan and Wong (2001)

Research in China
From the perspective of semantic analysis, Zhang Meisuo (2000) conducts research of the usage of cohesive devices in the expository writing for Chinese EFL learners and finds that they have problems in reference and always shift the pronouns within or between clauses. Wang Liqin (2006) describes the general features of the use of first person subject pronouns and explores the changes in the use of first person subject pronouns in argumentative writing by Chinese English major students. Yu ping and Cheng Congmei (2008) apply Relevance Theory to analyze tentatively of the pronoun reference as the cohesive device. FANG (2016,2017,2020) explores the Relativizer Omission by Chinese EFL Learners from various aspects.
From the perspective of semantic analysis, Niu Hongwei (2004) points out 3 binding features of English reflexives and the subject orientation for Chinese EFL learners. Zhang Guiju (2005) points out that ambiguity in reference is common errors in students' writing. Tang Shiyi (2005), Jing Rongqin (2007) survey and analyze the application of the Anticipatory It-Clause for Chinese. Jia Tingting ( 2008) discusses the gender mixed use errors of the third person animate singular English pronouns by Chinese EFL learners in spoken English. Chi Dan (2008) explores pragmatics of the demonstrative pronoun. Wang Chunlan (2009) points out that pronoun-shift result from mental distance and self-politeness. Zhang Ning (2006) testes advanced Chinese learners in their acquisition of English reflexives in mono-clausal sentences to find out their processes (Li, 2012). Li Fang (2012) implements an empirical study of the misuses of English pronouns among higher vocational school students. Li Li (2017) implements studies on different uses of pronoun it in cross-sectional learner corpora.
From the perspective of contrastive studies, Ma Guanghui (2001) conducts a contrastive rhetorical analysis between English essays written by Chinese students and American students and finds that Chinese students have problems in the use of pronouns. Yuan Jin (2004)  Those fruitful findings have shed light on pronoun research and enlightened researchers of related areas. However, no corpus-based study of WIC in Chinese learners' writing has been found so far.

Research Question
WIC play a vital role in indicating interpersonal relationship in English language. Their employment is very common for native speakers, but as EFL learners, are Chinese college students skillful in employing them? Therefore it is necessary to reveal their use feature in a provided situation. On the basis of the above reasons and consideration, the research questions are formulated as follows: What is the characteristic of the employment of WIC in Chinese college students` English writings in terms of frequency, sentence types and clusters?

Subjects
In order to conduct the research and probe into the above questions, all the subjects of this study are randomly selected from the classes the author teaches in 3 different colleges for the past 6 years, the details are shown in table 2.

Objects
As shown in table 2, the researcher has collected the writings and classified them into 6 groups, forming the object corpus after procedures stipulated in 3.4. The 580 students were given the topic "The most unforgettable person I ever know" on the Pigai.net at the beginning of the term as the following directions required: For this part you are allowed 30 minutes to write a short essay about "The most unforgettable person I ever know". You should state the reasons. Write at least 120 words but no more than 180 words.
All the collected compositions share the following common features: firstly, it is the student`s last version that is gathered into the self-built corpus. As above information shown, the composition of "The most unforgettable person I ever know" is not a limited time task. The students can accomplish it at any time within duration of three months or so and since the Pigai system can automatically mark and feedback those essays, hence the students can polish it at any time before the deadline. So there are many inversions of an individual composition from the same author, it is the last inversion before the deadline that is gathered as the research object. Secondly, these objects are accomplished in a very relaxed atmosphere because they are just after-class practice designed to improve their writing competence. There are usually 6-7 pieces of such compositions in an academic term in my teaching schedule. The students are required to finish them at any time with any reference available but are forbidden to plagiarize others` previous essays. Hence the students can accomplish them in a very relaxed atmosphere without interference of other components occurred in the test and match such as nervousness and anxiety. Thirdly, all these essays have not been revised and polished by the instructor, so they can serve as the authentic corpus that reflects the students' true writing style and competence.

Procedures
Firstly, the researcher analyzes all the writing of 6 groups (see table 2) on the topic "The most unforgettable person I ever know" in terms of content and correlation to the topic and deletes unqualified 50 essays. The left 580 pieces, which contain 5621 Word Types and 101372 Word Tokens, are chosen as the sample object resource. Secondly, the researcher applies the following analysis items of the AntConc3.3.5 to search the feature of WIC in turn: Concordance, Concordance Plot, Cluster and Word List and gets corresponding database.

Instruments
This research is facilitated by the employment of 2 pieces of software: AntConc3.3.5 and Pigai software. Pigai software is an online system which can be used to automatically scan the parameters of a student's English composition to make accurate and objective judgments and comments based on the comparison of the distance between the object compositions and the standard Corpus. Besides scores, it can provide specific feedback and suggestion in the syntax level, which can facilitate the students` revision. Its main function in this research is to comment and record all the traces of the leaner`s writing behavior. While AntConc3.3.5 is a kind of powerful software which is widely used by researchers who investigate language patterns in different languages, and by language teachers and students all over the world to look at how words used in texts. Its main function in the present study is to describe the corpora on the whole and to retrieve all the WIC selected in self-built corpus. It is composed of the following 7 analysis items available for phraseological research: Concordance, Concordance Plot, Cluster, Word List Concordance, File View, Collocates, and Keyword List. Among these, the first 4 items are main tools applied in this study. Apart from these tools, Excel is added to record the number of each category of WIC respectively.

Data Processing and Analysis
Firstly, the researcher utilizes the "Concordance" of AntConc3.3.5 to count the number of the employment of all the 5 words in WIC in the following terms shown in figure 1 in the self-built corpus and get 517 records of sentences.

Figure 1. Research terms by concordance
Secondly, the classification of these records is implemented according to the standard shown in table 1, the detailed information about the number and frequency of each word of WIC is presented in Table 3.
Thirdly, the researcher analyzes all the retrieved sentences in terms of sentence type. In order to facilitate the statistics and comparison, the researcher further classifies the attributive clause into 9 sub-types according to their nature and the role WIC and their antecedents play in higher matrix clause. But some sentences are wrong grammatically and involve many defects. Therefore, it is hard to decide the sentence type for them. As to such sentence, the researcher tries to guess the author`s initial intention and classifies it (see sample 5, 6). But to those hard to recognize, the researcher marks them as "unknown, wrong" (see sample 7, 8).

Sample 5
A person who weared a suit with glasses, walking confidently in front of me. (restrictive attributive clause modifying subject, wrong) Sample 5 is wrong in grammar. It can be either changed into "A person wore a suit with glasses, walking confidently in front of me." or "A person who wore a suit with glasses, walked confidently in front of me." According to the comprehension of the thought mode of Chinese learners, the researcher classifies this sentence as "restrictive attributive clause modifying subject, wrong".

Sample 6
However, for me, a person appear to my head who is beautiful and kind. (restrictive attributive clause modifying subject, wrong) Sample 6 also has defects, but based on logic, the researcher assumes its initial intention as "However, for me, a person who is beautiful and kind appears to my head" and then classifies this sentence as "restrictive attributive clause modifying subject, wrong".

Sample 7
In my memory, the most unforgettable person I ever know who is my angel. (unknown, wrong) For sample 7, it is better to delete "who". Therefore, this sentence is marked by "unknown, wrong".

San Mao, who is my most unforgettable person that is a famous woman writer and traveler in Taiwan and whose original name is Chen Ping. (unknown, wrong)
In sample 8 it is easy to identify the subtype of "who" clause but hard to decide "whose" clause. It can be either improved as "San Mao, who is my most unforgettable person, is a famous woman writer and traveler in Taiwan, and her original name is Chen Ping." or "San Mao, whose original name is Chen Ping, is a famous woman writer and traveler in Taiwan and my most unforgettable person." Hence the "whose" clause is marked by "unknown, wrong" The likewise procedures are implemented in turn by Concordance, Concordance Plot, Cluster and Word List. As table 3 shows:

By Concordance
1) In total number, there are 517 records of employment of WIC, occupying 89% of the effective subjects, which demonstrates the Chinese learners use them very common.
2) In terms of employment frequency of individual words, the employment of "who" lists top 1(496), occupying 95.9%, and the rest 4 words in turn are: whose (10), whom (8), whoever (3), "whomever" (0). This indicates that the "who" is the most popular and common word for the subject and "whomever" is the least one.
3) In terms of classification of sentence type, there are 448 contribution attributive clauses, 23 object clauses, 31 cleft sentences, 12 special questions independent clauses, 2 adverbial clauses and 1 subject clause, which indicates that the employment of WIC in attributive clause is the most familiar function for these learners. And their use in nominal clause (such as predicative clause and subject clause) and adverbial clause is the least familiar field for them.

4)
In terms of the role that WIC and their antecedents play in higher matrix clause, the first top 3 in turn are: predicative (206), object (158) and subject (49). This indicates that the learners prefer to use simple sentence structure such as "There is one person who helps me a lot." or "She is the person who helps me a lot." 5) In terms of correctness, the total appropriate usage is 88 times (occupying 34.8%), which demonstrates that a large number of students have not mastered the application of them at all.

By Concordance Plot
The same terms as shown in figure 1 is searched by Concordance Plot and the detailed information is presented by table 4. As table 4 shows: 1) The number of students who employ WIC in their writing is 353 out of 580, occupying 60.7%, which indicates that a large number of them have the habit of using WIC to depict interpersonal relationship.
2) 123 students have employed WIC more than once in a short essay, which shows that they have pragmatic consciousness of them.
3) The use frequency of WIC of individual student is unbalanced with 39.3% remain "zero" and 21.2% employ them more than once and the top one is 6 times (see sample 9) in this study.  The terms as shown in figure 2-3 is searched in turn by clusters/n-Grams, the detailed information shows that:
2) Combined the result in figure 2-3 with the text analysis, the most repetitive sentence pattern (65 times) is: I have met many people who are really worth recalling.
met a great many This may indicate that many students regard this sentence structure as good and then apply it as an introduction one in the first paragraph. In addition, it also demonstrates that the learners prefer to use WIC in simple sentence structure rather than complicated one, and "many people" ranks top 1 of the clusters of "who". Note. The number of frequency of "who" in this figure does not match that in table 2 because there are 4 sentences that carry double "who" in it and be considered as 1 record by concordance and 2 records by wordlist.

By Wordlist
Results of wordlist shows: That the self-built corpus contains 5621 Word Types and 101372 Word Tokens, which means the average lexical frequency in lexical density is 18.03, but WIC hit 517, this shows they are no doubt high-frequency words. In detail, the "who" ranks 35 in frequency of all the words, which further confirmed that it is very popular in this study.

Conclusion
In all, the employment of WIC in Chinese college student`s English narrative writings bears the following features: 1) As a whole, WIC can be regarded as common words for Chinese college students because of their high frequency in this study. But the distribution of individual word is relatively disproportionate-"who" attracts far more attention while the other 3 word as "whom, whose and whoever" attract little attention and "whomever" even attracts no record at all.
2) In terms of sentence type, the distribution of the 5 types is imbalance with too little use of adverbial clause and too much of attributive clauses. In addition, the learners are used to utilizing simple and identical sentence structure and some of them are highly repetitive. That is to say, they lack the skills of using WIC more complicatedly and advanced, such as in predicative clauses or adverbial clauses of concession. Furthermore, the distribution of sub-type of attributive is disproportionate too-predicative accounts for the overweight proportion and appositive attracts no attention at all.
3) The use frequency of WIC of individual student shows that a majority number of learners have formed the habit of using WIC to depict interpersonal relationship and their distribution is unbalanced too-with 39.3% remain "zero" and 21.2% employ them more than once in this study.
4) As to the clusters, the learners have formed the habit of preference use of "who" as relative pronouns elt.ccsenet.org English Language Teaching Vol. 14, No. 4;2021 above all. And some clusters are highly identical and simple. 5) To sum up, the majority of learners in this study can employ WIC consciously in their writing, but their usages are confined to simple words and structures with low accuracy. Therefore, the learner`s comprehensive competence of integrated employment of WIC should be improved.

Limitation of the Research
The reliability of the findings of this research is limited for the following reasons: Firstly, the source database is only limited to self-built corpus without international database in contrast, therefore, it is hard to identify the peculiar characteristic of WIC in Chinese college student` s English narrative writing without comparison. Secondly, the research method employed is relatively simple, mainly corpus-based quantitative method and text analysis, rather than integrated methods, consequently, some findings are mainly based on descriptive analysis and may be superficial and less convincing. Thirdly, the topic research object is only limited to "The most unforgettable person I ever know", which may be single and simple. Therefore, the use of WIC can`t be fully reflected in these writings. Fourthly, the classification of sentence pattern of a single sentence is not unique since some of them may involve many defects and hard to decide. Therefore, further investigation should base on larger variety of subjects and topics, more detailed analyses of the text. Moreover, qualitative and quantitative analysis rather than descriptive analysis based on the comparison of corpuses between Chinese learners and native learners can be taken into account as well.

Suggestions for Future Research
·To further research the features in more detailed aspects.
·To carry out comparison research.
·To attach more importance to experimental and empirical methods.


Application of computer technology in Aerobics Teaching and training

We know that aerobics exercise can have a good effect on our body function. Aerobics can improve the depth of our breathing. It can make the cells in every part of our body more active. Many experts believe that aerobics has gradually become people’s health dance. Many countries also hold corresponding aerobics competitions[1]. With the rapid progress of computer technology, the application of Aerobics Teaching and training based on computer technology has become a hot topic. This paper describes the current situation of aerobics teaching. This paper finally puts forward the application of computer technology in aerobics teaching.

Introduction
With the gradual improvement of people's living standards, people are constantly accelerating the construction of spiritual culture. Many people want to have attractive figure. Many girls want to have a symmetrical body. Experts found that aerobics exercise can make the proportion of the body more coordinated [2]. It can make people's body more plump. It is worth noting that aerobics is suitable for every age group. Aerobics can improve people's physical and mental health. It can cultivate people's good sentiment.
The effect of aerobics is also recognized internationally. Many countries also hold aerobics competitions. Aerobics is a popular sport. Many schools also encourage students to learn the art of aerobics (see Figure 1). However, people gradually found that the traditional aerobics teaching process is very boring. With the development of computer technology, people pay more attention to the application of computer-based aerobics teaching and training. On this basis, this paper puts forward the main problems of the application of computer technology in aerobics teaching.

Single teaching method
Indoor teaching is the main way of traditional aerobics teaching. Many schools only teach students the basic theory of aerobics. Students seldom have the opportunity to guide their study after class. Therefore, the author thinks that today's aerobics teaching method is very single [3]. Theoretical courses will only urge students to study mechanically. This kind of teaching method can not adapt to the study of sports. However, it is still difficult for many schools to correct this problem.

The renewal speed of theoretical learning is slow
We know that aerobics is also in constant development. Our country's aerobics training center's theory study project is gradually developing. The renewal of theory courses in many schools is very slow. Aerobics has a unique artistic thinking. The study of Aerobics must be guided by theory. If students lack theoretical study, their Aerobics movements will not be very standardized. This will also affect students' learning of sports knowledge.

The school does not pay attention to aerobics
Many schools do not attach importance to the study of physical education. They think that students' cultural achievement should be the first [4]. This also leads to the lack of sports network curriculum resources. This problem also reflects the negative impact of the concept of exam oriented education in China. This is a very worrying problem. This also leads to the physical quality of students can not reach the health standard of ordinary students. There is no doubt that it will delay students' study of sports. week course each semester. This shows that students' physical education courses only occupy 36 class hours. In the ordinary physical education curriculum, the probability of Aerobics learning is also very low. Many college students will not even choose bodybuilding as their own sports. It is not conducive to the development of Aerobics resources (see Table 1 and Figure 2).

3.1 Open Education Culture
Traditional aerobics learning is limited to indoor and outdoor environment. Teachers need to teach students some traditional theoretical knowledge. The teacher shows the related movements of Aerobics for the students [5]. These teaching models are very rigid. The network technology of computer equipment can provide an open learning mode for Aerobics Education. Students don't have to be limited to the study of theory indoors.

Extensive learning resources
With the gradual progress of network technology, people can find a variety of information resources in the network. We know that aerobics is suitable for a wide range of people. Adults can also learn the artistic movements of aerobics. People can use the Internet technology to log in some aerobics course resources website. The application of extensive learning resources can help us better find our own learning style.

Personalized teaching mode
Many students don't like the classroom style of some teachers. It is difficult for teachers' old educational ideas to be recognized by students. This also led to a lot of students tired of the classroom psychology. The electronic virtual classroom using network technology can provide personalized teaching services for students. Students no longer need to accept the teacher's forced learning. Students can also find the corresponding teaching services in the network .

Automatic computer management
The study of aerobics is different from that of ordinary science subjects. Students not only need to understand the network aerobics course carefully. Students also need to complete self-study after class. The network course based on computer can realize automatic student management. Students need to shoot an aerobics action video offline [6]. This video should be submitted as an offline assignment. If the student does not submit the assignment, the computer will automatically deduct the student's credit.

Aerobics teaching courseware based on material library
Many schools have some Aerobics Education Courseware. Some colleges also have their own material library. Teachers can extract the courseware of aerobics teaching they want from the material library. Material library can even form the teaching courseware of Aerobics automatically under the operation of teachers. Moreover, the content of these courseware is very rich. The text and pictures of sports events are very clear.

Aerobics community based on campus network
Every school has its own sports organizations. Many students will spontaneously form these aerobics learning groups [7]. Every sports association has its own webpage and website. The website mainly includes the introduction of the association and the introduction of enrollment. In these websites, students can also find relevant aerobics teaching resources. Junior students will also find some dancing videos of seniors. People can express their opinions in various forms in online forums. Students who have studied aerobics will also share their learning experience in the forum. They also share their own learning videos. This is conducive to help other students smoothly break through the difficulties of Aerobics learning. Some students can also get to know each other in the forum. They can share their learning experience with each other. The forum has gradually become the main topic.

Establishment of course selection module
The course selection module of Aerobics Teaching System in Colleges and universities should be divided into three parts. The first part is the information of the course. Personal information mainly includes class information, class location and teacher. The second part is the professional information of course selection. If the students don't meet the course selection conditions of the major, they can't choose the course. The third part is to modify the information. When students are not satisfied with the course they choose, they can modify the relevant information in the web page.

Establishment of teaching module
The teaching module mainly includes four parts. The first part is the notification of the message. The college will inform all students of the course changes. The second part is the courseware download notice [8]. Both students and teachers can download relevant courseware from the website. The third part is the theory database. Students can find relevant teaching resources in the database. The fourth part is video teaching course. It is also a part of teaching resource management.

Online interactive module
All physical education teachers in the school have relevant user names in the teaching system. If students encounter problems in the process of learning aerobics, they can put forward their own problems in the network. When teachers log in to the teaching system, they can see the specific content of the students' questions. Teachers can choose to answer questions online or offline. Teachers and students can talk to each other in the teaching system through the interactive module.

Network conditions of campus network
We found that many school students think that their school's campus network is very poor. Many students want to log in to the school's information portal [9]. They take a long time. This shows that the login speed of the school's information portal is very slow. This also shows that the network condition of campus network is very poor. It is worth noting that the aerobics network learning can not use lowquality campus network.

Improvement of teachers' guidance role
In the traditional aerobics training process, teachers need to guide students to complete the study. Teachers are disseminators of knowledge. They need to play a stronger guiding role. With the help of computer technology, students can complete their study independently. This leads to the decline of teachers' teaching status. Teachers need to give full play to the role of guidance. This shows that offline courses are more difficult for students to trust.

Potential safety hazards need to be on guard at all times
In the network, we can see that many people lost their health because of sports learning. The artistic movements of aerobics are really beautiful. However, if the sequence of actions is disordered, students' body will be hurt [10]. Therefore, in the process of aerobics teaching, we need to always be on guard against the emergence of security risks. There is no doubt that this is a very important issue.

Conclusion
Aerobics learning can not only help students keep healthy, it can also help students keep mental health. With the help of computer technology, we can improve the quality and efficiency of aerobics teaching. At the same time, we also found the efficiency of the application of computer technology in education.


s2fieldsofstudy: Education Physics

text:
Determination of refractive index on three mediums based on the principle of refraction of light

This study aims to develop a tool to determine the refractive index and height of objects in three media based on the principle of light refraction. The method used was an experimental method. The results showed the refractive index values of the three media were quite accurate when compared to the absolute refractive index. The relationship of the angle of the incident ray was directly proportional to the angle of the refractive ray. The angle of light produced will be greater if the value of the given beam angle was greater. Thus, the set of refractive index laboratory tools developed is said to be good and suitable to be implemented in schools to explain the concept of the refractive index of light.

Introduction
Physics is a science-based on experiments [1]. One method of learning physics using tools in learning is the experimental method [2]. Experimental activities in the laboratory can perform smoothly if laboratory equipment is available [3]. But the fact is not all schools which have this equipment completely, or, in several cases, there are not all physic concepts which have experiment tools such as in refracting concept. This factor caused many students who have difficulty in problem-solving [4].
One of the physics concepts that are abstract, and needs to be practiced through experiments is the refraction of light [5]. Besides, the number of misconceptions on this concept required students to conduct an experiment activity in order to make it easier to learn [6]. Light has many phenomena that student can learn [7]. The fundamental concepts of refraction of light are based on the results of invention by Dutch scientist Willebrord Snellius, the well-known as the first law of Snellius and the second law of Snellius [8]. The refraction of light events occurs in optical substances such as air, water, and glass [9]. Refraction of light occurs because of differences in the speed of light on the two media. The speed of light in a dense medium is slower than the speed of light in the air medium [10]. In general, the speed of light in all materials is slower than the maximum speed in a vacuum [11].
The most teachers explain of light refraction topic, usually, using glass filled with liquid and then inserted a pencil [4]. However, that activities are only able to show the refraction phenomenon, but do not explain the relationship between variables such as the angle of incidence, the angle of refraction, and the refractive index. So, its usefulness to solve related problems in daily life.
The teacher has done a simple experiment, by using a simple laboratory tools, to provide students with a good learning experience on the topic of refractive index. As the result, student will be able to understand the refractive index topic better [12]. The refractive index experiments can improve student understanding, especially in the discussion and implementation of the optics [13]. The refractive index  [14]. The refractive index is a measurement of speed of light in a liquid compared to when it is in the air [15] and is one of the most important optical properties of a medium [16]. The refractive index in a medium is often defined as the ratio between the speed of light in a vacuum to the speed of light in a medium [17].
The physics laboratory in schools has developed a simple tool to test the refractive index of the liquid [18]. In Indonesia, most teachers prove the concept of refraction using only a pencil dipped in a clear glass filled with water. There are several researches of laboratory tools that used to determine the refractive index, including with a CD lattice, refractometer, parallel plan glass, and optical fiber.
Previous research carried out a refractive index experiment tools with a fairly complex step or set up. However, when the tool is implemented in laboratory activities, there are several obstacles for example, it can only be used to determine the refractive index in one media [4]. The novelty of the research is that the set of tools developed is derived from general equipment that can be found in everyday life. The equipment made does not require relatively expensive costs. This tool can measure the refractive index on three mediums at once, namely, on the medium of air, solid and liquid. In the solid medium, the researchers used a glass that had a thickness of more than 15 mm. Besides, researchers also put an object in the water so that students who will do the practicum can measure pseudo height and actual height of objects in the water that is affected by the refractive index. The purpose of development the tool is to make it easier, for students, to determine the refractive index by only using one experiment tool to in three mediums at once.

Methods
The research method used is an experimental method where the delivery of teaching is done by experimenting to find out for yourself what has been learned. Students can find for themselves what was learned individually [19]. This method starts by designing a light refraction tool with steps like in Figure  1. The making this light refraction tool starts by first determining the tools and materials, which consist of a cookie jar, glass, laser, protractor, ruler, object, wooden board, water, and rope. The light refraction device that has been created is shown in Figure 1.  The design considered the intended uses, practicality in the use and utilization of the experimental set in the learning process. The tool was designed to be used in three mediums which are air, glass, and water. This tool works based on the Snellius' refraction principle which reads incident rays, normal lines, and refractive rays located on a flat plane. A comparison of sinus of incident ray and its refraction is a fixed number that is called the refractive index [20]. The incident beam from the laser will be refracted or deflected to form a refractive angle (the angle formed between the refractive beam and the normal line) [21]. The comparison of the angle of the incident ray and the angle of the refractive ray this then produces the refractive index value. The value of the refractive index depends on the medium in which it passes. The tight the medium is traversed, the bigger the refractive index. Whereas if the media being passed is loose, the value of the refractive index is smaller [22]. The refractive index value of a medium can be determined using the law equation Snellius [23].

Result and Discussion
The refractive index experiment tool has been made. The repeated testing is carried out to ensure that this tool can be used and worked correctly. The measurements, the data that are collected used the toll, are measuring the angle of the incident ray and the angle of refractive ray. Three mediums passed consist of air, glass, and water at the same height. The doing variations in the incident light are at an angle of 30°, 45°, and 60°. The results of the observation are shown in Table 1. Each variation of the angle of the incident ray has a different value of the refractive beam angle. At the altitude 5 x 10-2 m with angles coming up it 30° produces a refractive angle value 15° and 20°. The highest angle of the refractive ray is valued 35° at the angle of incident ray 60° while the lowest angle of the refractive ray is valued 15° at the angle of the incident 30°. So, if the angle of the incident ray is enlarged, the value of the angle of the refractive ray will increase. Based on the data, it can be concluded that the incident ray is directly proportional to the refractive light, and this is also the opposite [24]. By using the measurement data, it can be calculated the height of the object and the refractive index of each medium. This result can be seen in Table 2. The highest object is at the angle of the incident ray 60° with a refractive ray angle of 35° which value is 12.3 x 10 -2 m, while the lowest object is at the angle of incident ray 30° with the angle of refractive ray 20° which value is 7.9 x 10 -2 m. Table 2 shows the measured height of each object. The actual height of the object becomes deeper at the surface of the water than the height of the object's shadow. This is caused by the refraction of light that passes through the surface of the water, which causes bending of the light. So, that objects look closer than in fact, and the object is located far from the surface of the water [8]. This bending light occurs due to differences in the density of the medium through which light is passed [25]. The height of each object on the surface of the water is affected by the angle of incidence. The greater the angle of incidence, the deeper objects looks from the surface. Conversely, the smaller the angle of incidence, the shallower object looks to the surface.
The results of calculations on the refractive index have slightly different values in each angle variation of the incident ray. The average yield of the refractive index produced does not have much difference from the absolute refractive index for the three mediums. The absolute refractive index in the air is 1 and for glass is 1.5 [26]. While the absolute refractive index in water is 1.33 [27]. This is not in accordance with the average refractive index produced where the refractive index of water obtained is 2.43. The result shows if we compare it with observations relating to the refractive index on the glass medium as did previous research by Faradhillah, the resulting refractive index has the same value [28].
The water refractive index obtained from this study, when compared with previous studies conducted by Radiyonoa has a different value [29]. Based on the results of research, the error value between the measurement and reference results in the refractive index of the air reaches 6%, while the refractive index of the glass reaches 0%, but at the water refractive index, the percentage of errors reaches 8.2% with the absolute refractive index. The difference in the refractive index is due to the result obtained is a comparison of the angle of the incident ray and the refractive ray angle with its absolute refractive index so that the resulting refractive index is a relative refractive index [30]. Besides, the difference in the refractive index is caused by the speed of light speed in each medium (different samples), where the speed of light at vacuum speed is faster than the speed of light when passing through a medium [27].
The inaccuracy in making tool and measurements can also cause the value of the refractive index of water is different in every angle of the viewing. However, the refractive index in the other medium does not experience too much difference in value from the absolute refractive index value. The advantage of our tool uses three different mediums to determine the refractive index and can measure heights of the image and heights of objects that are in the water. The drawback of the tools we use is less precision in the results of the third medium refractive index, which causes the value of the refractive index far different from the absolute refractive index. In further research, it is recommended to modify the tool so that the resulting refractive index value corresponds to its absolute refractive index, especially on the third medium (water).

Conclusion
We have succeeded in conducting research on making a tool from simple materials and equipment that are easily found in everyday life to determine the refractive index and height of objects on three mediums (air, glass, and water). Based on the results of the study, the relationship of the angle of the incident ray is directly proportional to the angle of the refractive ray. Based on the results of the study, the relationship of the angle of the incident ray is directly proportional to the angle of the refractive ray. The refractive index on denser media will have a greater refractive index value. Only the refractive index value of water has a greater value than the glass medium. However, the air and glass medium have a value that corresponds to the absolute refractive index. Thus, the set of tools made can prove the value of the absolute refractive index and is said to be suitable for learning of students.


Design an expert system for students graduation projects in Iraq universities: Basrah University

Received Apr 9, 2020 Revised Jun 18, 2020 Accepted Aug 5, 2020 A graduation project is a form or work that the study authority requests from the student to measure what he made during the study. Designed an expert system for students’ graduation projects at the University of Basrah for students who are obligated to submit a project that qualifies them to graduate from the university. The system works according to a set of requirements, the most important is first: The student's possession of a high rate that qualifies him for the project. Second: he must possess half of the skills required for the project provided that it includes at least one programming language example (c ++, java, PHP, c #, etc ...). The system has many features that help the Supervisors and Students Committee to manage students' projects efficiently. System is built as a web-based system, with access limited only to the university's local network.

INTRODUCTION
The graduation project is a project that the study authority requests from students before obtaining a university certificate, graduate attributes have been taking momentum since the early 20th century. One of the most commonly used definitions of graduating attributes (GAs) suggested by Bowden et al. says: "Graduate attributes are the qualities, skills ,and understandings a university community agrees its students should develop during their time with the institution" [1]. the aim of which is to identify the extent of the student's understanding of what has been studied within the corridors of the university, and to measure his ability to creativity [2], and there are some universities suppor tthe work for more than one student [3], and this must be completed Research in a specific period under the supervision of a university professor [4]. Most computer science programs at the undergraduate level require a compulsory "graduation project" course that students must take in the third or fourth year of study.
In the College of Computer Science and Information Technology, each student is required to develop a project, implement a model system, and write a research report in one semester. The projects are distributed according to mechanisms that depend on points (student average, skills that he owns it in the field of Computer Science and Information Technology) supervisors should assist their students to complete the project, and guide them through the main stages of the graduation project. Thus, supervisors and other participants will be involved to track student work and progress [5][6][7]. For this purpose, we design an expert system, based on the students' skills the have to make an appropriate decision in distributing projects to students. An expert system is "a computer program that uses knowledge and inference procedures to solve problems that are ordinarily solved through the human expert" [8]. With the rapid growth and unfold of

METHOD OF SYSTEM
To the better of our knowledge, software for managing graduation projects is an incredibly new idea. A tremendous deal of studies of an exploratory and descriptive nature is needed, as shown in Figure 1 representing the overall system structure for the distribution of graduation projects to students. The main components of the system are the knowledge base, inference engine, and a workspace. The knowledge base of the system performs a key role in the method of decision-making by efficiency storing the domain knowledge and student Information. Temporary results may be stored in the workspace. The inference engine is a program, which infers the knowledge available within the knowledge base [23][24][25]. Distribute student projects, the system intends to represent a common framework that implements a generally accepted basic structure of academic projects. Steps to make the system:

Steps of students' registration for the projects 2.1.1. Student registration
Each student logs into the system through the student number and the password that he receives through the system administrator, where he is a number. The student is made up of (7) numbers, such as (1204351), which is the same as the student's ID number, and the secret number is composed of (18) numbers, which are randomly generated by this function such as (435727893387780658) show in Table 1.

Projects proposed by the scientific departments of the college
All graduation projects submitted to the system are presented to the student on the projects page, which contains all the project details these are (name of supervisor, project title, main objectives of the project, brief description of the project, requirements, number of students required for the project).

Student registration process on projects
Before the registration process, if the student is the first time to enter the system, a list of skills will appear in him on the registration page at projects the student must determine the skills he possesses, and these skills are added to the student's information and based on which they are tested with the project's skills. The registration process takes place after the student determines the skills that he possesses. The student can register only by specifying the skills. After specifying the skills, each student is allowed to register on only three projects, and he is not allowed to register on more than three. To ensure the student's right, the student system can print a report that contains the student's name, student number, and projects that have been registered and also contain QR code contains the name of the student and the projects registered on it to prevent fraud and forgery in projects. Show in Figure 2.

Amending the projects of the registered person
After giving the administration a period for its students to change their options, the student can enter this page and choose the project where. He who wants to change and replace the project he wants and uses this mechanism with the rest of the projects. After the end of the period, the page is closed, as a student cannot change his options.

Amending student information
The student has the right to only change the skills. As for the rest of the information, it is modified by the administrator, because it is downloaded to the system automatically through a text file on the student registration page and at the same time it can be modified show in Figure 3.

The powers of the person responsible for the system and the mechanism for distributing student to projects 2.2.1. Add students
The names of students who are entitled to register on graduation projects are entered, and they are Input process is two ways: a. The first method: adding his application group as a single payment by receiving an excel file from the concerned authority responsible for sorting students who are entitled to register on graduation projects and transfer it to a text file, where the entry is as a text file and this type is used if the officer wants to enter his request group. b. The second method: adding a single student, where the entry is by the administrator, he enters all the data manually and uses this type in the case of entering one student. The student's information entry is in both cases (student number, student name, student average, and his password). Where a number is generated for each student in both ways (a random 11-digit secret number that the student uses with his number to log into the system) show Figure 4.

Student information
The system contains a database for all student information that the system needs in the process of distributing graduation projects to students and includes (student number, student name, student rate, student password). Enables the system to perform: a. Performing student information modification or student deletions by clicking on the field you want to delete. b. Print a report containing all students 'information. Where student numbers and secret numbers are distributed to students through this report, each student takes his password through the student number where (Each student has a unique number, "ID number", whereby a student can enter the system when he obtains the ID number and password from the report at the committee responsible for the projects). As shown in Table 1.

Add a project
The system administrator enters graduation projects with full details (project title, professor name, number of students required for the project, project goals, project description, as well as the skills required for each project).

Modifying project information
The project information can be modified by searching on the title of the project to be modified, then correcting the information and clicking on the amendment button, and the project can also be deleted by clicking on the delete button.

Registering students on the project and controlling the process of registering on projects
Every student has the right to register on three projects published by the system administrator. The registration process for projects and the process for modifying projects are controlled through a control panel where a specific period of time is given to the students to complete the registration process on projects. When the specified period ends, the system administrator can lock the registration process as the student cannot register. As well as giving a specific time to students to process the amendment of student options and when the specified period ends the system administrator can lock in the modification process as the student cannot amend the project data.

The process of distributing projects to students
Projects are distributed to students according to controls and conditions, whereby the distribution depends on the student's average rate and the student's second-class skills and number students required for each project. But each of the above conditions depends on the other condition to conduct the project distribution process.

2.3.
Steps of project distribution STEP1: Students are ranked from the highest rate to the lowest rate through the database using language SQL STEP2: The skills required for the project are compared with the skills that the student possesses, and to achieve the requirement that the student accepts the project that the student chose in the previous entry process, he must possess half of the skills required for the project Provided that it includes at least one programming language example (c ++, java, PHP, c #, etc ...). STEP3: The required number for each project is examined and based on the required number, students are added to the project and upon reaching the required number the student is transferred to the second project registered on it and so on, the mechanism of action of the system: 1. Students' skills and the skills required for each project are retrieved. Before adding the student to the project, check the required number for the project. If the required number of the project is incomplete, the student will be added to the project. If it is incomplete, the student will transfer to another project from which the projects are registered. If (Required Number of project <= Count project in Data) Add (); Else Tested on Another Project (); 6. In the last stage before adding any student with his project to the database, check the database with the student not already present to avoid duplication of data. The official can print a report containing the final distribution of projects on students with full details (the name of the supervisor and the student involved with the project and the required number ( shown in Table 2. understanding, knowledge, directions, intentions, and technical capabilities. This paper presented a web based distribution graduation-project management system. The impulse behind the implementation of such a system has been the realization of the important role of the graduation project for preparing students to the real world, and probe of the number of administrative tasks involved on the part of faculty members and students. For that reason, the manual procedure for distributing graduation projects to students has been replaced by an automated system for managing and distributing projects graduation show in Figure 5. This system has some limitations where the students can`t change the project after distributed projects for students via the system and Difficult to Determine the ''best graduation project based on the student's Interests. In spite of this, the system has many advantages due to its importance and urgent need in the university which includes: a. Coordinating and managing the processes of the graduation project course. b. Solve conflict in the projects, meaning choosing more than one group for the same project. c. The system provides security for the student by obtaining a printed report containing the QR code containing the student's personal information in addition to the three options that he chose within the projects presented. d. Develop Knowledge Base System to distribute graduation projects to students at the University of Basrah Reducing all (administrative) procedures and related processes. e. Increasing effectiveness and developing performance in technical operations and information services. f. Easy and fast information management. g. Eliminate the factor of the direct relationship between the two parties to the transaction or reduce it to the maximum extent possible, which leads to limiting personal effects and influence. h. It is more economical than it is in the traditional system, as there is no need to print project selection forms and distribute them to students. i. Reducing time and effort as students do not need to come to college to receive a form to choose graduation projects and deliver them after filling them. j. Canceling the paper system and replacing it with the electronic system because of its flexibility and the ability to quickly correct the errors that occurred.

CONCLUSION
The system is designed at the University of Basra for students who are obligated to submit a project that qualifies them to graduate from the university. The system has achieved the basic idea that depends on the principle of distributing student projects based on the student's programming skills and the student has a rate that qualifies for the project The system performs well. result of the system helped in the following ways: (1) it simplifies interactions with the domain experts; (2) it reduces the complexity; (3) it provides effective modularization. The idea on which the expert system" Graduation Project" is built has sizeable potential, and the opportunity to develop and improve. as future work, you can add social network analysis in competition-based learning. Can develop the system as future work by adding: (1) Add guidelines for college students, wherein the projects committee can post recommendations for students. (2) Permit supervisors to create one listing of tasks, to be used as a template for a multitude of different projects. (3) Add a news bar, wherein the Head of the Graduation Committee could, for example, placed up updates concerning new regulations, or modifications to the undertaking timeline, etc. (4) Allow the Head of Graduation Committee to place up progress evaluations for students and supervisors to fill out and ship lower back over the system; Implement the automated event handler subsystem.


CURRICULUM REFORM IN THE DECENTRALIZATION OF EDUCATION IN INDONESIA: EFFECT ON STUDENTS’ ACHIEVEMENTS

This study examines the estimated effect of curriculum reform in the Indonesian secondary education after the implementation of the decentralization policy in 2001. Whilst decentralization reform is argued to be positive for the improvement of school quality and efficiency due to more autonomy given for provincial and local governments, the empirical evidence on such reform towards the improvement of students’ learning outcomes is very limited. Using the propensity score analysis, this study shows that the curriculum reform has not produced a substantial return in the aspect of improved learning outcomes. This finding resonates with the evidence from previous studies on the impact of decentralization on the education quality in Indonesia. Additionally, other findings present a positive effect of pre-school attendance on students’ performance and the crucial issue of persisting gap on the education quality between regions even after almost twenty years of decentralization in the country.

INTRODUCTION
As one of the most prominent education reforms in many countries, education decentralization has become a popular topic in both scholarly and policy level of discourses. Associated closely with power distribution between different levels of government, decentralization in political aspect is perceived to undergo simultaneously with the democratization agenda (Channa, 2016;Jeong, Lee, & Cho, 2017). The phenomenon also experienced by Indonesia, where after the hit of Asian financial crisis in 1997, the country had been through a rough democratization process. Ending the thirty-two years of authoritarian government under Suharto regime, Indonesia entered the Reformation Era, remarked by decentralization of most government functions, including education (Kristiansen & Pratikno, 2006;Pradhan & de Ree, 2014;de Ree, Muralidharan, Pradhan, & Rogers 2014;Yeom, Acedo, Utomo, & Yeom, 2002). Though the process of reformation had also external pushes from international agencies such as World Bank and International Monetary Funds, it was believed that decentralization was a wise decision considering the change in political system in the country which demand more democratic participation from its people.
In education, similar with other public sectors, decentralization is multifaceted and has both political and economic aspects (Jeong et al., 2017). Decentralized education has different forms depend on the national context of implementation, where two forms of the process could be seen in governance or more administrative aspect also in fiscal instrument, resulted further in different evaluation approach of such implementation (Jeong et al., 2017;Subijanto, 2010). Jeong et al., (2017) argued that while some countries might be both politically and fiscally centralized, some others might only have one aspect of decentralization. Diverse facets of decentralization practices can be also distinguished in particularly two forms: decentralization of education to local governments with focus on transfer of authority (Channa, 2016), and to schools in regards of 'school-based management' in the aspects of administrative, professional, community and balanced controls (Channa, 2016).
Apart from the devolving schemes, decentralization are argued to be a very important formula that could improve the provision of education services and in the end increase the quality of education (Channa, 2016;Jeong et al., 2017). Theoretically, by positioning educational decisions towards local governments, the decisions would be better meet the students' needs compared than homogenous standard set by the central government. Competition is expected to be increased among service providers, to ensure the delivery of high quality schooling. The accountability measurement of education delivery would also enhanced with the increasing participation from diverse stakeholders, including parents and community.
Since 2001, the administration of education in Indonesia has transformed from previously very centralized one towards decentralized system (Kristiansen & Pratikno, 2006). Responsibilities in management and financial aspects of public education in early childhood, primary and secondary levels have been moved from central to local government. This change of policy was introduced as well by many governments in other countries, believing such strategies would benefited the improvement of education services delivery. In Indonesia, the central part of decentralized decision making in education is the School-Based Management (SBM) policy, where the empowerment of principals, teachers, also the involvement of parents and community are expected to have positive effects for autonomy and accountability in education delivery, and in the end produced better learning outcomes (Rahman, 2019).
In economics of education perspective, the school inputs remain the main part where government policy could play its role in education investment (Brewer & McEwan, 2010). Teacher certification, school operational assistance, teacher competence test, in-service teacher development program, and one-year preservice teacher training, are some of the major policies taken by the Indonesian government to enhancing the quality education in the country (Kurniawati, Suryadarma, Bima, & Yusrina, 2018). With the heavy investment on public education, teachers have benefited the most from the increase in education spending, from their increased salaries, also from more hiring and trainings, although, the investment seems to be ineffective towards the goal of better students learning (de Ree et al., 2015;Kurniawati et al., 2018).
On the other hand, curriculum reforms were part of the undergoing changes in Indonesian education, and it has strong relation with the dynamics of national level students' assessment in the country, as can be seen in Table 1. Curriculum reform is also a main part of the decentralization policy instrument, where in 2006, the school-based curriculum was introduced (Qoyyimah, 2018;Rahman, 2019). In 2006 School-based Curriculum, teachers are given more freedoms to plan the teaching and learning that is based on the condition of students also the school condition and environment (Wahyuni, 2015). In 2013, the Characterbased Curriculum was introduced to further complement the 2006 School-based Curriculum with emphasis on students' competence that should be accompanied with the strong character as well critical thinking, however the implementation of curriculum in schools level are still in development process.
By focusing on the curriculum reform in 2006 as significant feature of education decentralization in Indonesia (Amirrachman, Syafi'i, & Welch, 2009), this study examines the effect estimation of the curriculum reform to students' achievement in secondary schools by using the data from Indonesian Family Life Survey 5 (2014)(2015). The main research question of this study is: "Has the curriculum reform implementation since 2006 in Indonesia effected students' performance?". With the evidence from Indonesia, the results of this study are expected to contribute to empirical inquiries of education investment and policies in developing countries, particularly under decentralization agenda.

METHOD
The data used in this study is from the fifth wave of Indonesian Family Life Survey (IFLS), which is an ongoing longitudinal survey that collects data at community, household, and individual levels (Strauss, Witoelar, & Sikoki, 2016). There has been five waves of the survey so far. The first wave, IFLS1, was conducted in 1993-1994, and the sample represented around 83 per cents of Indonesian population in 13 out of 25 provinces in Indonesia by that time. The second wave of the survey was done four years after the IFLS1, and there was additional survey conducted in 1999 towards the 25 per cents of the subsample on the impact of economic crisis (IFLS2+), and the following wave was fully conducted in 2000. The IFLS4 was conducted in 2007-2008, and the last wave, IFLS5 was in 2014-2015. For the purpose of this study, the data of adult information on individual level where education related information in IFLS5 is utilized.
Sample is constructed through several steps. First, as the focus of this study is to see the curriculum reform in secondary education as part of decentralization, the respondents chosen here are those who graduated from junior and senior high schools between 1988-2015. Second, the observations in which national examination scores are not available were dropped. Third, the year of taking national examination is used as the dummy variable for the curriculum reform measurement. It is important to note that students take national examination with the curriculum first introduced to them when they enter school. For secondary schools, it means there are three years gap of the introduced curriculum to their year of taking national examination. As the new curriculum named "School-based Curriculum" as part of decentralization reform was introduced and formally legalized in 2006, therefore students who experienced the curriculum reform under decentralization policy were those who took the national examinations after 2009. Those who took the examinations before that were the control group in this study. The variables from IFLS5 Book 3A (Adult Information Part 1) that are chosen as measurement in this study are shown in Table 2.
In this study, propensity score analysis is conducted to estimate the effect of curriculum reform as part of education decentralization on students' performances in secondary level. The analysis is one technique of causal effects' estimations that allow valid casual inference based on defining the counterfactual group through a quasi-experiment on observational data (Cordero, Cristóbal, & Santín, 2018). With respect to observed covariates, both propensity score models were administered to reduce the selection bias by balancing the treatment and the control groups to look like the full sample (Adelson, 2013;Guo & Fraser, 2014;Rosenbaum & Rubin, 1983;Xie, Brand, & Jann, 2012).

Development of National Level Assessment
The analysis process started with preliminary descriptive analyses for all variables after the deletion of missing cases (see Table  3), and then the study conducted the ordinary least squares (OLS) regression with and without control variables as the first model, the propensity score matching model as the second model, and the propensity score weighting models as the third one (see Table 4). For the propensity score weighting models, logistic regression analysis was conducted with covariates to examine the adjusted differences in characteristic of students who experienced curriculum reform and not, include to estimate the propensity scores.
The next step was to conduct a propensity score analysis with weighting process that is often called by inverse probability of treatment weighting (Fan & Nowell, 2011;Hong, 2012;Rosenbaum & Rubin, 1984). In the end, the OLS regression analysis were conducted to estimate the effect of curriculum reforms in three aspects: average treatment effect (ATE); average treatment effect for the treated (ATT); and average treatment effect on the controlled (ATC).
Based on the R-squared of all models, the weighting procedure presented the most representative model that could explain the effect estimation. The analysis then went further by estimating the effects of curriculum reform in overall subjects (mean score), also in each individual subject (see Table 5). The final conduct of analysis was as presented in Table 6, where the groups of treated after the curriculum reform is divided in yearly basis (from 2009 onwards), to see the development of policy on curriculum reform implementation effect on annual level. Table 3 presents the descriptive analysis of variables used in this study. After the data is constructed, the number of observations of secondary school students with national examination scores available are 6081, with the mean of total score is 7.029 out of 9.998 maximum. Among all subjects, Bahasa Indonesia score has the highest mean whilst English has the lowest one. Among observed sample, around 54 per cents are women, more than 68 per cents attended public schools, with average hours spent in schools are 6.2 hours. More than fifty per cents also attended kindergarten, and those who took national examination after the curriculum reform in 2006 was implemented contributed to more than eighty per cents of sample. This unbalanced condition between the control and treatment groups are resolved further through the propensity score analysis. The main research question of this study is answered through the conduct of several models of causal inference as seen in Table 4. After the balance of observation numbers between the treatment and control groups, from Table 4 we can assess that the robust model that can explain the data analysis better is the propensity score weighting. For the causal inference, it is shown that curriculum reform has significantly negative effect to students' performance. However, as the variable curriculum reform is only divided in two categorical of students who took examination on 2008 (and before) and 2009 (and after), further appraisals are needed to present more detail pictures on this result, as the analysis is exercised through the division of reform by yearly basis (see Table 6). The analysis also presents that students who attended kindergarten tend to perform better than who did not. It supports the argument of investment on early childhood education in Indonesia (Nakajima, Hasan, Jung, Brinkman, Pradhan, & Kinnell, 2019). In model 3 and 4, it is also shown that female students comparatively have lower performance than their male peers. Also, the student who come from schools in lower HDI region, tend to perform lower, and it pictures the gap of quality education among region in Indonesia, which has been an issue for so many years (Amirrachman et al., 2009;Kurniawati et al., 2018;Yeom et al., 2002).

FINDINGS AND DISCUSSION Findings
In Table 5, the analysis of propensity score weighting on Average Treatment Effect (ATE) is presented. It can be seen that curriculum reform has a relatively small effect on students' performances in Bahasa Indonesia. However, this might be explained by the fact that national language proficiency of students are relatively higher. For negative effect estimation of curriculum reform, the most prevalent result is in students' mathematics performance.
It also estimated that the effect of attending kindergarten is significant on students learning outcomes in mathematics and English, while not significant for Bahasa Indonesia's performances. The results also show consistency in the unequal quality of education among regions. To explain the insignificant effects and some negative effects of curriculum reforms on students' national exam score from year 2009-2015, detailed analysis is conducted and presented in Table 6.   Table 6, the data of students who took national examination is divided into yearly basis (before 2009 with 2009, before 2009 with 2010, cont.). The results present that generally there were no statistically significant effect of curriculum reform on students' performance in overall national examination score from 2009. However, in 2013, the estimating effect of curriculum reform on students' performances are statistically significant, in negative direction. The possible explanations of these results could be on the fact that started in 2013, there was a policy intervention on the conduct of national examination, where the examination questions have more types and there were also more invigilator during the exams. However, there were problems in the conduct of national examination in 2013 due to the mismanagement from the Ministry of Education, which had resulted in the delay of the examination in many regions (Suryadi, 2013). This affected students psychologically, because they had prepared for the examination and on the day of the exam, the exam sheets were not arrived yet. Another cases were the incomplete exam sheets or misdistribution of exam sheets.

Discussion
The origin of decentralization in Indonesia could be traced far before the so called 'Bing Bang' decentralization took place in Indonesia due to the significant economic and political transition during the beginning of the new millennia Fitrani, Hofman, & Kaiser, 2005;Hofman & Kaiser, 2004). The concept of 'regional autonomy' was included in the Constitution Law in 1945, the recognition of extensive autonomy in different tiers of government was also introduced in the Government Law No. 1/1957, but finally the system needed to be centralized again due to many political unrests. Even during the New Order regime where the government was heavily centralized and authoritarian in nature, the local autonomy was once again passed into legal base under the People's Consultative Assembly in 1974. Law No. 5/1974, even in practice, the exercise of decentralization was introduced in 1995 (Fitrani et al., 2005;Skoufias, Narayan, Dasgupta, & Kaiser, 2011). It was the fall of New Order regime as the aftermath of Asian Financial Crisis in 1997 that had resulted in a major breakthrough of governance system in Indonesia.
The structural adjustment requirement from the international agencies added the extreme transformation of Indonesia from previously one of the most centralized systems to one of the most decentralized ones (Hofman & Kaiser, 2004).
In education sector, the decentralization started took place after the enactment of Law on Decentralization in 2001, marked by the transferred administrative and fiscal power and responsibility for health and public education to districts governments, where teacher salaries, general school operational costs and management are handled in district level (Leer, 2016). In 2003, the Constitution Law No. 20 was enacted and it stated the reform of education educational system that should be based on democratic, decentralized and socially just principles (Rahman, 2019). The school-based management policy has designed the autonomous school governance where principals have primary responsibilities to work and collaborate with other school stakeholders, such as teachers, parents, local communities under the establishment of school committee (Leer, 2016). In ensuring the better and more heterogenous education delivery to diverse students across the country, the curriculum that based on competency occurred in 2004, and finally the School-Based Curriculum was legalized in 2006 with features of decentralized curriculum were emphasized on development of localized curriculum with more autonomies given to teachers in doing so (Qoyyimah, 2018;Rahman, 2019;Yeom et al., 2002).
Due to the pro and contra in the mandatory national examination as main instrument of quality education assessment, for example, after the Supreme Court Decision in 2010, there had been fundamental changes in the graduation criteria and the percentage of national examination score that is being counted as passing criteria (Alhadza & Zulkifli, 2017). In 2013, the government also had made several changes in the national examination to reduce leaking, cheating, and score manipulations (Alhadza & Zulkifli, 2017). Whilst in 2015, the Computer-Based Testing was introduced to enhance the efficiency and effectivity of the conduct of national examination, also to ensure fairness and reduce malpractices of the examination (Kurniawati et al., 2018). After the new administration of government in 2019, the appointed Minister of Education and Culture has finally decided the abolishment of national examination in Indonesia starting from 2021 to ensure the rights of continuing education for all students, and change the evaluation through competence assessment and character survey. However, in response towards Covid-19 disruption, the government decided that this year (2020) the national examination for primary and secondary levels are cancelled (Wajdi, Kuswandi, Faruq, Zulhijra, Khairudin, & Khoiriyah, 2020).
Regardless heavy investments and decentralization efforts in making better access to quality education, the returns to that investments are argued to be the main problems that need to be addressed. The little experience of local democracy, unclear legislative guidelines, lack of local capacity building are mentioned as the unpreparedness of decentralization policy that has resulted the failure of policy implementation (Amirrachman et al., 2009). Further, the corruption issues also have proven to diminishing the effectiveness of public spending on education in Indonesia (Suryadarma, 2012). In the case of effects of decentralization policies towards students' learning, many empirical inquiries have shown very limited, almost zero evidences of how such policies could improve Indonesian students' performances in national and international level assessments (del Granado, Fengler, Ragatz, & Yavuz, 2007;Chen, 2011;de Ree et al., 2015;Kurniawati et al., 2018;Kusumawardhani, 2017;Leer, 2016;Sirait, 2016;Suryadarma, 2012).
This study has the objective to provide a robust analysis on effect estimation of curriculum reform under decentralization policy on students' learning outcomes in Indonesia. In policy level, there are different instruments that government can exercise to achieve the goal of decentralization efforts, and curriculum reform is one of the significant feature (Amirrachman et al., 2009). Curriculum reform reflects the expectation of educational changes, which would affect teacher education, teaching content and practices, school leadership, even infrastructure, and most importantly educational outcomes (Qoyyimah, 2018). The change in curriculum, with the aim to increase better learning, certainly has complex mechanism that connect each other, therefore there is should be no simple direct correlation of one aspect under the change.
However, under the context of decentralization, the autonomy of school and teacher is central on curriculum reform. By granting autonomy to schools in varying their curriculum depends on their students' needs and local context, students' performance in the end should be improved. Some evidences can be seen in the case of curriculum reform with school autonomy plays important role towards learning performances in England and East Asian countries (You & Morris, 2016).
From this research findings, we can see some important points to be addressed. First, there has been a very dynamic development in terms of curriculum reform and national examination in Indonesian education for the past twenty years. The reforms and changing policy, however, have gaps between the intention and implementation. Some argues that the policy initiatives have been changing depend on who are the policy makers rather than to serve the main purposes of making a better education system in the country (Suryadi, 2013). The policies have been politicized and unsustainable, therefore the roots of low quality education have not been resolved yet. For example, as discussed in the findings part, the issue of chaotic conduct of national examination in 2013 and 2014 was one impression of the poor management in Indonesian education system during that period (Lestarini, 2014).
Second, whilst there are evidences where curriculum reform under decentralization brought positive effects to the students' outcomes (Rahman, 2019;You & Morris, 2016), the underlying condition is adequate understanding and quality of teachers as the main education resources to implement the policy direction. Teachers' professionalism and capacity development to follow the reformation should be highlighted, however, from the evidences of school-based management and decentralized curriculum in Indonesia, lack of socialization and sufficient supports have hindered the accomplishment of curriculum reform (Rahman, 2019;Retnawati, 2016). The issues of teachers' quality and ability to adapt the reform are mentioned to be the challenges of improving students' learning outcomes in Indonesia (Rahman, 2019). With higher expectation and burden for teachers in adjusting the needs of their students also in fulfilling the targets set by the government, the realization of making the reform effective and achieving its' goals is not an easy task to do.
Third, the results also presented the important aspect of early childhood education as investment on school readiness, which will be beneficial for students' learning performance in later years. This could be one example of fruitful policy implementation on increasing early childhood education access as part of Indonesian government priorities over the last decade (Nakajima et al., 2019). However, it should be noted that the issue of inequality of access and quality education among different group remain crucial challenges to be addressed. The gap between students from higher and lower quintiles, also from urban and rural areas, still hamper the achievement of development goals in education in Indonesia. The significant results on students' outcomes difference based on the regions where the schools are located continuously resonates the evidences from previous studies on decentralization impact in education quality in Indonesia, and the issue of inequality among regions in Indonesia (Aditomo & Faridz, 2019;BPS, 2019).

CONCLUSION
Indonesia has been experiencing a tremendous increased of investment in public education during the past two decades, together with the decentralization on its governance. While positive appraisals were given to the country in presenting a 'quite good' case study in developing economies of decentralization reform, the empirical evidences of return of investment in increasing quality education is still being questioned. This study reveals that, similar with other interventions of decentralization policy in Indonesia, the curriculum reform has not produced a substantial return in the aspect of improved learning outcomes. Further, this study discusses the issue of unsustainable policy direction and teachers' ability to perform the curriculum design and objective, future studies might explore other dimensions from different perspectives.
Curriculum implementation under decentralized education, expect schools and teachers to develop their own approaches that fit the needs of their students. It also expect students to develop their competences while also improving students' learning outcomes. Therefore, the issue of teachers' quality and their ability to conduct the curriculum reform content is crucial to be addressed. The sufficient supports from the national and institutional levels should be prioritized, therefore the teachers would not be further burdened by the heavy administrative concerns, but could focus on cultivating their professional skills and judgment to carry out the reform successfully. As also argued in other decentralization studies, the accountability measurement on any intervention should be added and taken into serious manner, so the investment could have resulted in enhancement of students' performance and overall quality of education.