Teaching Strategies as a Powerful Hidden Curriculum: A Review Study

A hidden curriculum arises during the learning process especially when the interaction between teacher and student. How the teacher chooses to educate students can convey messages that are hidden and not hidden. The message has a positive or negative effect. That's why teaching strategies are a powerful hidden curriculum. This review study includes some articles to prove the existence of a hidden curriculum in teaching strategies chosen by teachers and their impact on students. Linking existing educational theories and expert opinions is a way of reviewing this article. This review study is expected to give consideration to the teachers in choosing the right teaching strategy to achieve the learning goals.


INTRODUCTION
The teacher as a learning resource is obliged to provide a creative and innovative learning environment for student learning activities in the classroom. One of the activities that teachers must do is to select and determine strategies to achieve teaching goals. Orlich et al.(2010) The term strategy implies thoughtful planning to do something. Murdiono (2012) Teaching strategies are plans and ways to implement learning activities so that the basic principles of learning can be carried out and learning objectives can be achieved effectively. Iskandarwassid, & Sunendar (2008) There are four basic strategies in learning, namely identifying what is expected, choosing and defining procedures, methods, and learning techniques, establishing norms and minimum limits of success.
The main objective of choosing the right learning strategy is the realization of a good quality education. The quality of education is the main issue discussed in various countries. PISA (the OECD's Program for International Student Assessment) is one of the institutions that assess the quality of education in reading, mathematics, and science. PISA assessment can be used as a reference in improving and developing the quality of education, especially for countries that get low scores. Ii (2018) Students need to develop a set of abilities to succeed in the information age called 21st Century skills. Tican & Deniz (2019) Adapting to social values, professional life, and life itself is difficult for students. Ahmad (2017) Students can gain knowledge effectively if the teacher is more creative and innovative in learning activities. That is the reason for the development of teaching strategies from time to time.
Consciously or unconsciously in learning strategies, messages are hidden and not hidden. Maria (2015) values that are embedded in students who are not included in the curriculum and include informal or formal influences, because socio-cultural structures, families, street groups, personalities in educational relationships are referred to as hidden content. This hidden content called the hidden curriculum. Henson (2015) The task of understanding clear concepts about the hidden curriculum is difficult because it carries subtle messages that go on and on. To prove that the hidden curriculum is a powerful force in any school, and that can strengthen school, state and local reform efforts and school missions that are stated to be not difficult.
Learning strategies as a hidden curriculum can be illustrated as teachers use cooperative learning models. cooperative learning has a hidden message that is the existence of social contacts that can work together or not students in the group. So, cooperative learning must pay attention to the knowledge, attitudes, and behaviors that students have in order to run effectively and efficiently. The illustration also proves that the hidden curriculum can have positive effects and negative effects. Therefore, teachers must pay attention to the strategies he uses.
This review study aims to analyze the experiences of the teachers in applying the learning strategies chosen through a review of the literature from various published research articles so as to give the teacher the right teaching strategy to achieve the learning goals. Galvan & Galvan (2017) In reviewing the literature it will be easier to identify the main theories that apply to topics of interest. Cohen, Manion, & Morrison (2018) Journals, abstracts, and online titles to search literature form material relevant to the chosen topic. Jesson, Matheson, Lacey (2011) One concept we have emphasized so far is that literature reviews should take a critical approach. Fink (2014) A review of the literature is method for identifying, evaluating, and synthesizing existing bodies from completed and recorded works produced by practitioners, researchers, and scholars. The discussion focus of this article is to prove the existence of a hidden curriculum in the teaching strategies used by teachers in educating their students. The selected literature is several books and articles that are accessed online, especially through ERIC, Scopus indexed open access journal, and PNRI (National Library of the Republic of Indonesia). Books and articles are collected and selected that are relevant according to the focus of the discussion. There are two types of literature used, namely the main literature that contains articles containing phenomena to analyze the existence of hidden curricula, and the second literature as reinforcement and comparative study material. This review study is processed qualitatively by analyzing some of the literature that will be reviewed with theories and opinions of experts in education.

RESULTS AND DISCUSSION
The existence of a hidden curriculum can be proven by analyzing the impact of teaching strategies on students. We can identify the impact of teaching through the results of research on teaching strategies carried out by the teacher. Therefore, there are two steps that will be taken, namely reviewing the teacher's teaching strategy and analyzing the hidden curriculum. Review Teaching Strategies Used. Example 1 -Teaching Strategies Approach The term "approach" in the teaching strategy refers to the orientation of the implementation of learning. The teaching strategy approach used by the teacher is a traditional or teachercentered approach and a modern or student-centered approach.
Ivić, Gortan, & Gortana (2016) The traditional approach in school is teacher-oriented which transfers specific verbal information for each lesson, while students are passive observers who listen, copy, memorize, and repeat. The results of observations regarding the learning approach are teacher-centered from the research Zohrabi, Torabi, & Baybourdiani (2012) state that the problem is students do not use their potential, the main focus is to get students to carry out the state mandate test well rather than serving students' needs.
Anagun (2018) The teacher is the main actor who shapes learning for students and has an important role in applying innovative approaches to learning. Ivić, Gortan, & Gortana (2016) Student oriented teaching implies that students work together with the teacher to choose teaching goals and teaching assignments based on authentic problems and students' prior knowledge, experience and interests. The study of teaching strategies using a modern or student-centered approach will be discussed by giving an example application in point 2.

Example 2 -Teaching Strategy Style
We know that each subject has different characteristics. Rodriguez said the students have more negative attitudes toward math and science. Laine, & Näveri (2019) Teachers a central role in advancing social interaction and a positive atmosphere in their classes. In their research state that the emotional atmosphere can be built to be positive when the teacher invites students to talk about mathematics and their own understanding of each other. Rourke, Main, & Ellis (2013) Games technology in the form of handheld game consoles focuses on specific academic skill development has the capacity to engage students in learning and in turn produce positive academic results. The result Rourke, Main, & Ellis (2013) research state that the handheld game consoles capacity to engage students in sustained learning and collaborative opportunities that most impressed the educators. Anton (2013) Gasing is a tool suitable for teaching and learning the concept of time measurement. Anton state that learning sequences are generated to support the emergence of student strategy as a model consisting of playing traditional top tops and turns, measuring time using hours, determining the duration of the event.

Analyze The Hidden Curriculum
CHIŞIU (2015) The contents of an educational or curriculum element are not always tangible or measurable. There are terms like hidden curriculum or cache content for some of the values transmitted through the school. Glatthorn et.al (2019) The concept of a hidden curriculum gives the idea that schools do more than just transmit knowledge. As in the first example about the impact of teaching strategies using a teacher-centered approach, which has a negative impact on students. Sharpe & Curwen (2012) The next level of the hidden curriculum assumes the child's role as a student is to receive knowledge from a character who controls and supervises what is learned. Çubukçu, Z. (2012) Students must not act without teacher approval or approval. The teacher can be subjective in practice about which courses and subjects are important. The teacher gives a secret message to students whether the subject matter or not. The second example provides an overview of negative views on mathematics. The teacher can control this view by providing a pleasant learning atmosphere so that it can support learning. Teacher creativity in teaching is very necessary to motivate students in learning.
The hidden curriculum that developed in the school environment basically supported the formal curriculum carried out in schools. The hidden curriculum provides a profound experience of personality, norms, values, beliefs that are not fully explained in the teaching carried out by the teacher.  The importance of a hidden curriculum in the learning process is to present its part in a variety of educational experiences, which leaves a strong impact on social, behavioral, ethical, spiritual values, and intellectual.

CONCLUSION
Teaching strategies have a very strong influence that affects students. Hidden curriculum can have negative or positive impacts. The hidden curriculum will influence the development of students' attitudes, behaviors, and knowledge. Therefore, the teacher must pay attention to the use of his teaching strategy, especially reviewing the hidden curriculum that will appear. Primary students have special characteristics than students at other levels. We can find these special characteristics in terms of emotional, interaction, language, and physical and psychological growth. Learning objectives will be more easily achieved if the teacher knows the characteristics of students. But the learning objectives will also be difficult to achieve if the teacher does not understand the characteristics of elementary school students. Therefore, the teacher must master the pedagogic ability to help the learning process.
Professional skills must also be mastered by the teacher. This ability is related to the teacher's mastery of the subject matter. The success of learning is also determined by the ability of teachers to understand and develop subject matter.