Penelitian ini bertujuan untuk menghasilkan perangkat pembelajaran fisika yang layak untuk melatihkan keterampilan berpikir kritis peserta didik SMA. Penelitian dilaksanakan pada semester genap tahun ajaran 2018/2019 di SMA Wali Songo Mantup Kabupaten Lamongan. Desain pengembangan yang digunakan mengacu pada desain 4-D. Metode pengumpulan data yang digunakan meliputi observasi, tes dan angket. Teknik analisis data yang digunakan meliputi analisis validitas, analisis kepraktisan, dan analisis keefektifan. Hasil penelitian menunjukkan: a) validitas perangkat pembelajaran yang dikembangkan berkategori valid (Dengan skor yang diperoleh 3,43; 3,47; 3,41; 3,36; dan 3,30 berturut-turut untuk silabus, RPP, bahan ajar peserta didik, LKPD dan instrument tes keterampilan berfikir kritis), b) kepraktisan pembelajaran berkategori baik (Dengan skor yang diperoleh 3,45; dan 3,49 berturut–turut untuk keterlaksanaan pembelajaran kelas XII MIPA 1 dan kelas XII MIPA 2, aktivitas peserta didik kelas XII MIPA 1 dan kelas XII MIPA 2 berkriteria baik). c) keefektifan pembelajaran berkategori tinggi (Dengan skor yang diperoleh 0,77; dan 0,76  berturut–turut untuk nilai N-gain keterampilan berpikir kritis kelas XII MIPA 1 dan kelas XII MIPA 2, respon peserta didik yang diberikan terhadap pembelajaran model guided discovery berbantuan simulasi PhET berkategori baik). Berdasarkan hasil penelitian tersebut, disimpulkan bahwa perangkat pembelajaran yang dikembangkan telah memenuhi kriteria valid, praktis, dan efektif sehingga layak digunakan untuk melatihkan keterampilan berpikir kritis peserta didik.

This research is aimed to produce physics learning instrument with appropriate project based learning models and be able to train critical thinking skills in senior high school students. The research was conducted in the second semester of 2018/2019 academic year in the Senior High School of  Wali Songo Mantup. Learning instrument developed refers to the design of 4-D. The data were collected by observation, tests, questionnaires and documentation. Data analysis techniques used include analysis of validity, analysis of practicality, and analysis of effectiveness. The results showed that: The results showed: a) the validity of the learning tools developed is valid (with scores obtained 3.43; 3.47; 3.41; 3.36; and 3.30 respectively for syllabus, lesson plans, teaching materials for students, LKPD and critical thinking skills test instrument), b) good practicality learning categories (with scores obtained 3.45; and 3.49 respectively for the implementation of learning in class XII MIPA 1 and class XII MIPA 2, student activities in class XII MIPA 1 and class XII MIPA 2 has good criteria). c) the effectiveness of high category learning (With scores obtained 0.77; and 0.76, respectively for the N-gain value of critical thinking skills in class XII MIPA 1 and class XII MIPA 2, students' responses given to the learning of guided discovery models aided by a good PhET simulation).. Based on the data obtained from the research results, it can be concluded that the learning instrument developed has satisfy the criteria of validity, practicality and effectiveness so that it is worth using to train critical thinking skills in students.