Abstrak: Tujuan penelitian adalah mengembangkan dan menerapkan tes diagnostik pilihan ganda tiga tingkat untuk mengukur pemahaman representasi grafik mahasiswa terkait esensi inkuiri sains dan materi optika geometri. Penelitian menggunakan metode campuran melibatkan 83 mahasiswa calon guru fisika di satu LPTK Sumatera Utara. Instrumen tes diagnostik terlebih dahulu didesain kemudian disempurnakan selama proses, direvisi, dan digunakan untuk mendeteksi dan menilai pemahaman representasi grafik mahasiswa calon guru fisika. Instrumen tes telah dikembangkan untuk dapat mendiagnosis dan memperbaiki kesalahan-kesalahan yang dilakukan calon guru fisika terkait dengan keterampilan mengonstruk grafik, menemukan kesulitan-kesulitan dalam membaca dan menginterpretasi grafik. Analisis data dilakukan secara kualitatif dan kuantitatif. Hasil studi menunjukkan pembacaan grafik dan keterampilan menginterpretasi grafik calon guru fisika masih belum memadai dan juga kemahiran dalam menganalisis grafik bergantung pada jenis grafik dan level atau tipe pertanyaan yang dikembangkan. Kata Kunci: representasi grafik, optik geometri, diagnostik tes ASSESSING OF UNDERSTANDING GRAPHICAL REPRESENTATION CONTENT GEOMETRICAL OPTIC USING DIAGNOSTIC TESTAbstract: The purpose of this study is to develop and apply three tier multiple choice diagnostic test to measure student's understanding of graphical representation about essential features of inquiry and content geometrical optic. The study was conducted using mixed methods and carried out with 83 prephysics teachers at a University of Teachers Education in North Sumatera. The diagnostic instrument was designed and then progressively refined, revised, and implemented to detect and assess student's understanding of graphical representation. Test instrument was developed to diagnose and correct the mistakes made by pre-service physics teachers about construction graphic skills, difficulties in the reading and interpretation graphical representation. The results of this study showed that graph reading and interpretation skills of pre service teachers were inadequate and also their graphing analysis varies depending on the type of graph and level type of question was developed.

The research, entitled "Analysis Students' Profile Mental Models High School on the rate of reaction" aims to obtain an overview of high school students' mental modelson the rate of reaction. The method used is descriptive research method, involving 32 students of class XI IPA who come from high schools in the district of Ciamis. The data was collected by a research instrument diagnostic tests, interview guides and documentation of study. Research results showed that students' understanding of the sub-microscopic level on the subject matter of rate of reaction is still low compared to other levels of chemical representation. Meanwhile, the category of mental models of the students on the subject matter of rate of reaction varied for each level of chemical representation. The chemical representation relationship with the category ofmental models of high school students on the subject matter of rate of reactionis almost in line with the previous analysis, which is based on the comparison betweenthe characteristics of the chemical representation and mental models of its catagory.

This study aims to determine the effect of guided inquiry learning for students' scientific literacy skills. The research was conducted at SMAN 24 Kabupaten Tangerang along January-June 2013. The method used was quasi-experimental, research subjects in this study were 77 students, divided into 2 groups: the experimental group and the control group. Research design in this study was the nonequivalent control group design. The instrument used was the science literacy test and observation sheet used. The research shows that students' science literacy for experimental group (mean = 54.49 and standard deviation = 18.67) was lower than the control group (mean = 57.63 and standard deviation of 14.37). After Mann-Whitney test (at the 95% significance level) α values obtained for 0.293 > 0.05. It can be concluded there is no significant difference between the average science literacy experimental group and control group students.

<span lang="EN-US">This study described the implementation of STEM-based science learning and performance assessment to the improvement of students’ thinking skill in Aceh, Indonesia. The purposive sampling technique was employed in this descriptive research. The respondents were 300 students at grade 11th academic year 2019/2020 which representing five public high schools in Aceh, Indonesia. The instruments used to measure the effectiveness of the implementation of STEM-based science learning were the rubric of habits of mind, observation sheets of performance assessments, and questionnaires. The finding presented the implementation of STEM-based science learning was able to habituate and develop students' habits of mind with an average score of 0.71 which included into high category. The average value of the overall STEM-based science learning implementation for the formation of habits of mind is 95.98% which categorized as good. It can be concluded that there is the success of researchers in implementing STEM-based science learning to form students' habits of mind.</span>

The aim of study was to develop the three-tier multiple choice diagnostic test that was conform with criteria of content validity and reliability to identification students’ misconception about chemical equilibrium. The method of this study was development and validation methods. Fourteen items were developed in this study. Based on the value of content validity ratio (CVR), all items were valid. The value of reliability of items were developed is 0.759, it means that items were acceptable. The respondents of this study were 5 validators who are lecturers from Department of Chemistry Education and 35 senior high school students’ who was learned subject chemical equilibrium. Based on analysis of students’ answer were based on a determination key could be found students’ misconceptions that on dynamic equilibrium, concentration of reactant and product are same as common misconception in the student (57.1%).