Effect of using problem-solving model based on multiple representations on the students' cognitive achievement: Representations of chemical equilibrium http://www.ied.edu.hk/apfslt/v17

The most difficult and easiest type of chemical representation is answered by the students in the experiment group

This study aims to find out the most difficult and easiest representation types for students and to know differences in chemical equilibrium learning outcomes in the experiment group and control group. Jhonstone (1993) says that studying chemistry should involve macroscopic, submicroscopic and symbolic representations so that when students learn will connect the three representations. Meanwhile, the research conducted by Chandrasegaran, Treagust, and Mocerino (2007) revealed that there are indications of students experiencing confusion about the chemical representation. Students are confused in connecting macroscopic representations with microscopic as well as having a limitation of caution about symbolic representations. This is what underlies the application of problem-based problem-solving model based on multiple representations. Selection of problem-solving model based on multiple representations is expected not only students can solve problems from the mathematical aspect, but can comprehend the concept of chemistry as a whole.

In this study, students were given tests of material that included macroscopic, submicroscopic, symbolic and mathematical representations, and contained cognitive levels from C1 to C4. Based on the results of the analysis using RASCH Model, from 27 questions given problems that are difficult to answer by students is a matter of No. 24 and No. 23. Problem No. 24 only successfully answered by 5 students while question No. 23 successfully answered by 7 students. Both of the above questions are a matter of loading the kind of mathematical representation. Students in the experiment group have difficulty in answering because of miscalculation. However, in the case of macroscopic, submicroscopic and symbolic representations, most of the students in the experiment group can answer it can be seen on the wright map above. While the most easily answered questions by students in the experiment group are questions No. 3, 10, 16, and 26. Problem No. 10 is a matter of symbolic representation, while No. 3, 16, and 26 contain symbolic and macroscopic representations.

The most difficult and easiest type of chemical representation is answered by the students in the control group

Students in the control group are taught with a problem-solving learning model without multiple representations. Based on the results of the analysis, of the 27 questions given, there are 3 questions that are considered the most difficult by students that are the questions of No. 7, 8 and 22. Each of these problems can only be answered correctly by one student.

The three questions above include submicroscopic and mathematical representations. While the most easily solved problem by students is the No. 1 and 10 questions that contain a type of symbolic representation. Based on this result, it can be said that the students in the control group have difficulty in solving the chemical problems based on multiple representations. This aligns with the result of research by Wang & Barrow (2013) indicating a learning method which did not integrate sub-micro and symbolic representations, results in the students having difficulties drawing and explaining the Bohr atom model in detail (and accuracy). According to Kosma & Russell (1997), this can happen because students do not understand how to relate submicroscopic representations to symbolic representations, whereas Krajcik (1991) says that students find interpretations of a phenomenon presented in a symbolic type that is difficult to interpret into appropriate submicroscopic types. Therefore, chemistry learning should be able to direct students to truly understand the submicroscopic representation so that students can understand the chemical concept correctly.

Differences in student cognitive achievement between experiment and control groups

Based on the result of difference test of student achievement between experiment and control group, obtained value of significance (2-tailed) resulted is 0.000 < from 0,05. This shows that there is a significant difference in the students' cognitive learning outcomes between the groups taught by the problem-solving learning model based on multiple representations and the problem-solving learning models without multiple representations on chemical equilibrium materials. Based on the result of posttest given, the mean score of the experiment group student is 73,42 while the control group is 55,08. The results of this study are in line with research conducted by Sunyono, Yuanita & Ibrahim (2015) who say that the learning method which integrates all three phenomena (macro, sub-microphone and symbolic) in chemistry education becomes very important in improving the students' reasoning abilities. Meanwhile, Guzel and Adadan (2013) showed that a learning method designed with comprehensive representation instruction may result in a more indepth comprehensive of chemical representation, which can be retained for up to 17 months. The results research conducted by Mocerino (2009) also show that treated groups in the form of multi-representation-based learning have higher learning achievement.