The 21st century learning paradigm emphasizes various skills that must be mastered by students, include problem solving skills. The problem solving skills are basically the main goal of the education process because students' skills are honed through problems so that students are able to improve various competencies. Experience in solving problems is needed by students after graduating from school and functioning at work.

As the part of natural sciences, physics learning aims to create humans who can solve problems by applying knowledge and understanding to everyday situations. However, preliminary research given to students of class XI Science at SMA Negeri 1 Waru, Sidoarjo showed that students' problem solving skills were relatively low. Therefore, problem solving skills are important to be trained in physics learning activities.

There areseverals learning models that aims to train students' problem-solving skills, for example Investigation Based Multiple Representation (IBMR) model. The IBMR model where developed by Siswanto (2018) has some steps of learning process, include orientation, investigation, multi-representation, application, and evaluation. The learning process in this study is arranged in accordance with the characteristics and steps of IBMR model. The IBMR model is expected to be effective to improve students' physics problem solving skills.

This study aims to describe the effectiveness of learning by using Investigation Based Multiple Representation (IBMR) model learning of Reflection and Refraction of Light matter. The research use one-group pre-test post-test design with 62 subjects of eleventh grade of SMA Negeri 1Waru, Sidoarjo. Data collection used physics problem solving test and questionnaire techniques. The data collection instrument was a physics problem solving test consisting of 7 problems about Reflection and Light matter. The effectiveness of the IBMR learning model was assessed from the N-gain test results of students' problem solving skills.

The analysis of N-gain values shows the increase of students' problem solving skills after learning by using the IBMR model with high N-gain values category. N-gainvaluesfor each classes are 0.75 for students from  XI IPA 1 class and 0.76 for students from  XI IPA 2 class. Overall, the average of N-gain value for two classes is 0.75.

Students’ response for learning by using IBMR model was positive. Table 1 bellow shows the students’ response for the learning. Based on the students’ response data in Table 1, students respond well to learning activities using the IBMR model with high average percentage (86.16%).

Tabel 1 Students’ Response to Learning by Using IBMR Model

Numb.

Related Aspects

Students’ Response Percentage

Well

Less Well

1.

Students’ interest in the learning component

88.17%

11.83%

2.

The renewal of the learning component

83.55%

16.45%

3.

The ease of solving the physics problem solving test after learning

82.46%

17.54%

4.

The renewal of the steps to solve the physics problem solving test

91.13%

8.87%

5.

Students’ interest in the learning by using IBMR model

85.48%

14.52%

 

Average of students’ response

86.16%

13.84%

The conclusion of this research are learning by using Investigation Based Multiple Representation effective to increase the physics problem solving skills shown by the high rate of N-gain value and the high percentage of students’ whom response well for the learning. Therefore, teacher could use Investigation Based Multiple Representation as an alternative learning model to improve students’ problem solving skills.