Measurement of mathematics problems solving ability using problem based mathematics question

The purpose of this study is to produce the valid, practical, and effective problem-based questions to measure the mathematical problem-solving abilities of eighth-grade students of junior high school. The materials used as the basis of development are system of linear equation in two variables and the Pythagorean theorem. The development model used is the Plomp model consisting of three stages; preliminary research, prototyping phase, and Assessment phase. Based on the results of these stages, 16 problem-based questions were obtained which are valid to the criteria of content, constructs and determined language, practically used by the teacher, and effective for measuring students’ mathematical problem solving abilities because they can direct students to identify problems, plan solutions, implement solutions, and need to carry out evaluations as indicators of problem-solving abilities.


Introduction
Mathematics as a basic science plays very important role in the development of science and technology. Mathematics is a mean of thinking to develop the power of reason as wells as logical, systematic and critical way of thinking [1]. It is also in line with National Education Minister that the ability of Mathematical Problem Solving must be acquired by the students[2] Students need to have problem-solving ability, through this abilitiy students can show their potential to solve problems around them. Mayer stated that problem-solving is a cognitive process directed towards achieving goals when there is no clear solution method for problem solvers [3]. It needs to be developed on students in order to avoid being desperate in facing a problem. The problem-solving ability can be obtained through several ways, one of them is by learning mathematical material and solving problembased questions. Vayor stated that on mathematics learning at school, problem-solving skill in K-13 is a competency to develop students' mathematics ability [4]. But according to Demitra, the difficulty of solving problems in mathematics still occur in school [4]. Reality also shows that the problem solving ability of mathematics owned by learners in Indonesia at this time each classified as low [5]. It is necessary to find a solution so that students no longer have trouble in implementing mathematical problem-solving. One of the ways is to complete learning devices that can facilitate students to gain experiences in problem-solving and provide evaluation tools that can measure the level of mathematical problem-solving abilities of students.
Problem-based questions need to be developed in order to provide opportunities for students to hone their problem-solving skills. Problem-based Questions are type of the questions with three common criteria, such as open-ended, contextual, and non-routine. Open-ended problem are questions  (2011), the development of problems with open type and contextual nature of non routine can be used as means of improving the quality of the learning process, especially to improve problem solving skills and also mean of asssemen in mathematics [7]. The adminsitration of these questions provide a chance for the students to think actively and creatively. Problems are useful for training one's thinking skills. One of the subjects that cannot be separated from problems was mathematics [8]. Problem-solving ability is one of the standard processes in mathematics learning [9] Students can improve their problem-solving skills specifically on mathematics problems. The statement was also strengthened by , which states that the development of the questions that focus on problem solving abilities need to perceived as media in mathematics evaluation and learning process[7].

Experimental Method
The research model used in this study is the Plomp which consists of three stages, preliminary research, prototype phase, and assessment stage [10]. At the stage of the preliminary study, analysis of curriculum or material and needs analysis were carried out. At the stage of prototype development, self-evaluations, expert reviews, one-to-one, small groups, and field tests were conducted [10]. Furthermore, at the assessment phase, a test with four indicators is made regarding to mathematical problem-solving abilities of students. The subjects of the study were eighth-grade students of SMPN Bangkinang Kota. The developed mathematical question is the material of linear system of two equations with two variables which is studied at eight grades in Semester 1 and the Pythagorean theorem which is studied at the same grade but in the following semester.

Preliminary Research Curriculum Analysis
The curriculum analysed in this study was the 2013. The problem based mathematical questions developed referred to the system of linear equations with two-variable and the Pythagorean theorem materials. The footage of the basic competencies and material indicators of the two-variable linear equation system and the Pythagorean theorem are as follows.  In Table 1 and Table 2, it can be seen that basic competencies are also developed so that students are able to solve problems related to the system of linear equations with two variables, and problems related to Pythagorean theorems and Pythagorean triple. Therefore, it is necessary to provide various problem-based questions to ease the teachers to obtain problem-based questions or as an evaluation tool.

Needs Analysis
Based on the results of interviews on six mathematics teachers in several schools in Pekanbaru, it was obtained information that the teacher needed problem-based questions. The questions can be used by the teacher to give variations on the questions in the system of linear equations with two variables, and the Pythagorean theorem materials. Numerous studies conducted by researchers in the field of mathematics education also require questions that can help measure problem-solving abilities. For example, the research conducted by Handayani related to the Effect of Missouri Mathematics Project Learning Model on Student's Mathematical Problem Solving. In the fifth stage of the Missouri project learning model, students will be given homework as a routine exercise conducted [11]. At this stage, the developed problem-based questions can be used by researchers.

Prototyping Phase
In the prototype phase, the questions that the researcher has developed will go through several stages. The questions developed are questions that are modified from various mathematical books. Problembased questions were developed in 16 questions which refer to the two-variable linear equation system and the Pythagorean theorem materials.

Expert Review
At the expert review stage, the researcher will describe the results of the analysis or review that has been carried out by experts in mathematics, language, and educational technology education. Some of the results of the problem-based problem validation stage by the expert also refer to the Zulfah article under the title "Pengembangan Lembar Kerja Peserta Didik Berbasis Problem Based Learning untuk Materi Matematika Semester 1 Kelas VIII SMP Pada Tahap Preliminary Research" [12]. The validity aspects used in the development of problem-based questions are as follows.  Based on the result of expert validity it was obtained suggestion dan revision as follows:

No Recommendation for Improvement After Revision
Language Aspect Fix the term, symbol and structure used. When the placement of the letter symbol on a triangle is anti-clockwise, you need to be consistent on it. 2

One-to-one
Prototype 2 was obtained after the revised results of prototype 1. Prototype 2 was used in a one-to-one test. One-to-one tests are conducted on 3 eight-grade students of SMPN Bangkinang Kota. The three students have different abilities ranging from high ability to low ability. Based on the results of the one-to-one analysis, it was found that students had difficulty in solving problems because questions were too long. Based on the results of the one-to-one test, a prototype 2 revision was carried out. The revised results on prototype 2 produced prototype 3. Next, this prototype will be tested to the small group stage.

Small Group
Prototype 3 was then tested in the small group stage. This stage involved 6 students with high, medium and low abilities. It was conducted so that the questions developed later can be understood by various characteristics of students. The footage of the results of the small group stage trial as follows.
Based on the results of the small group trial, a revision was then carried out, and prototype 4 was obtained. Prototype 4 was a problem-based question that was valid and practical after going through various stages.

Field Test
At the stage of the Field test, the valid and practical prototype 4 was used to evaluate the effectiveness of problem-based questions developed on students' mathematics problem-solving abilities. Indicators of problem-solving abilities used in this study are (1) Able to identify problems, (2) able to plan the problem-solving strategies, (3) able to implement the problem-solving plans, and (4) able to evaluate solutions given. The field test included 23 students.

Problems Based on Valid and Practical Problem Solving
Based on the results of the expert review and one-to-one test, the valid problem-based questions were obtained. The developed problem-based question consists of 16 questions with reference to the twovariable  using one formula but can be more or answer informally. The contents of the material asked were also in accordance with the type of school or school level, eight-grade students of SMP. The question developed is in accordance with the indicators of the material system of two-variable linear equations and the Pythagorean theorem. In the construct section, clear images are used, and there is a clear instruction for working on the questions. In the language aspect, the question sentence is adapted to EYD and is adjusted to the level of knowledge of the students. The practicality of problem-based question with the criteria that problem-based questions can be used by the teacher in providing diverse questions.

Problems Based on Effective Problem Solving
The problem-based questions developed are said to be effective because they can be used to evaluate students' mathematical problem-solving abilities because the answers given by students are in accordance with the indicators of mathematical problem-solving abilities. The problem-based questions developed as many as 16 questions which questions can also measure the problem solving ability, includes the skills of identidyng and understanding the problem. Planning ways to solve a problem, monitoring progress as the problem is tackled and then reviewing a solution to a problem [7]. The several questions that are produced are as follows Figure 1 and Figure 2.

Coclusion
Based on the development results of problem-based question were obtained 16 valid, practical, and effective questions for system linear equation with two-variable material and the Pythagoras theorem. Problem-based question validity was obtained through Expert Review stages and one-to-one trials. Experts in this matter are experts in the fields of mathematics education, language, and in the field of educational technology. Each expert consists of two people. These problem-based questions are said to be valid with predetermined criteria which are in accordance with the content, constructs, and One day, a Rabbit was boasting the turtle about who is the fastest walker. They decided to held a competition on the speed walk. A Rabbit and A Turtle race along a 5km straight road.The turtle starts the race earlier. It walks in the constant speed ½ km/hour. After the competition runs in four hour, the rabbit stats the competition. So, is it possible for the Rabbit to get the finish earlier that the turtle who started the competition four hour earlier?
On the following Wednesday, His Friends and Abdul will learn about pythagorean theorem. Therefore, in this meeting the Teacher assign the task to the students about pythagorean theorem . The teacher gives a rope in lenght 24 proportion. Abdul is asked to create Right Triangle. Is it possible for Abdul to create the Right Triangle? Explain the possible experiment in detail. The results of the problem-based prototyping phase conducted at SMPN Bangkinang Kota have similarities to the results of the development that the researcher did before at SMPN 13 Padang.

Acknowledgments
The researcher gratefully says thank to the Dean and the academic community for giving permission and support to researcher to complete this research. The researcher also expresses his gratitude to the Validator who was pleased to allocate valuable time. The researcher also thanks the Principle of SMPN Bangkinang Kota, Mr/Mrs Mathematics Teacher, and eight grade students who had participated in the implementation of this research. Thanks to the organizers of Ahmad Dahlan International Confrence on Mathematics and Mathematics Education 2019 for giving researcher the opportunity to publish this research.