This study aims to develop science practices instruction based on science critical thinking skill and tomeasure the effectiveness of the product toward critical thinking skill of elementary students in Gerunggang. The type of this research is research and development. The research instruments were documentation, expert sheet validation, observation sheet, feasibility sheet, and the test instrument of students' critical thinking. The subjects of this study were elementary school students in Gerunggang. The data subjects in this study were elementary school students and teachers in higher class. Based on the results of the development using the steps from Timpuslitjaknov, which include: (1) needs analysis, (2) initial product development, (3) expert validation and revision, (4) smaller-scale field trials, and (5) larger-scale field trials. Depelopment study of science with the results of the feasibility test by 3 expert (media, material, and language) the results are very feasible, smaller-scale tests and largerscale results with decent results. The effectiveness results of critical thinking skills are: 1) indicators provide simple explanations with N-Gain 0.40 medium category, 2) complete indicators with N-Gain 0.37 Medium category, 3) Indicators provide explanations with N-Gain 0.28 low category, so, it can easily be concluded that the result development of science practical instruction based on science critical thinking skill can enhance studnets' critical thinking skill for elementary school students.

This research is a descriptive qualitative research purposes to identify the level of basic teaching skills of the prospective primary school teachers through microteaching subject and to find out the problems of basic skills mastery of the prospective primary school teachers in STKIP Muhamamdiyah Bangka Belitung. There are 5 basic skills assesed, include: 1) asking skills, 2) strengthening skills, 3) providing variaton skills, 4) explaining lesson skills, 5) opening and closing skills. The subject of this research is 42 college students in fifth semester who took microteaching subjects in academic year of 2018/2019 as sample. This research was conducted for 6 months and the research instruments were in the form of observation sheets and interviews. The identification results of basic teaching skills showed that 1) mean score of asking skills is 80.36, categorized as excellent, 2) mean score of strengthening skills is 84.23, categorized as excellent, 3) mean score of giving variaton skills is 77.20, categorized as excellent, 4) mean score of explaining lesson skills is 75.51, categorized as good, 5) mean score of opening and closing skill is 77.45, categorized as excellent. While, the problems that is faced to the prospective primary school teacher on mastering the basic teaching skills are feeling nervous, thoughtless materials, the teaching process is not based on lesson plan set, and students lack of practice.

PENDAHULUANPendidikan Sains merupakan bagian dari pendidikan dan sangat dekat dengan kehidupan sehari-hari manusia, terutama untuk menyiapkan peserta didik yang memiliki kemampuan berpikir kritis, kreatif, logis, dan berinisiatif dalam menanggapi isu di masyarakat yang diakibatkan oleh dampak perkembangan IPA dan teknologi.Kepala Badan Penelitian dan Pengembangan (Balitbang) Kemdikbud, menyampaikan bahwa nilai PISA dan TIMSS Indonesia pada tahun 2015 masih rendah dibanding nilai rata-rata OECD, secara umum siswa Indonesia lemah di seluruh aspek konten maupun kognitif baik untuk matematika maupun sains. Hal ini juga diujikan pada siswa kelas 4 dimana 50% nilai TIMSS masih tergolong rendah, salah satu penyebab ketika diagnosis adalah kualitas pembelajaran. Untuk mengatasi masalah tersebut penting kiranya bagi seorang guru melatih siswa untuk dapat menciptakan pembelajaran yang akan melatih siswa meningkatkan kemampuan mengintegrasikan informasi, menarik simpulan, serta menggeneralisir pengetahuan yang dimiliki ke hal Abstract: This research aims to develop STEM (Science, Technology, Engineering, And Mathematics) based teaching material of electrical material for primary schools. This R&D study used 4D design; Define, Design, Develop and Disseminate. The instruments used are documentation, expert validation sheet, interview sheet, and feasibility test. Based on the first stage of the development; curriculum analysis, materials, and teaching materials, the second stage; specification of teaching materials design, the third stage; content analysis trhough construct validation with percentage value; 97% of the first material validator, 80% of second material validator, 82% of media validator, and 92% of language validator. The test was done to the small and huge scales of the sixth grade elementary school students with each average value was 96% and 99%. As the teaching materials user, teachers' testing response was conducted at the fourth stage with the average value of 100%. Based on the results above, it can be summed up that the STEMbased teaching materials with high feasibility can be used for learning teaching materials.