Critical Thinking is one of the most crucial skills that must be trained and improved in learning. This study aims to improve students' critical thinking skills using Project-Based Learning (PjBL) model with a STEM approach (STEM-PjBL) on optics topics. This study used a quantitative approach and one group pretest-posttest design. The sampling technique used cluster random sampling and the sample used consisted of 35 students of a class in a public high school at Samarinda. Data collection uses test techniques with 6 questions in the form of essays. The results of this study showed that using STEM-PjBL on optics topics can significantly improve students' critical thinking skills with sig values. (2-tailed) in paired T-test 0.000 and N-Gain 0.74, which is included in the high criteria. After learning, 34% of students are in the highly critical category and 66% in the critical category. The PjBL model with the STEM approach can be used to train the critical thinking skills of high school students.

Tujuan Pelatihan Pembelajaran STEAM bagi Guru IPA SMP di Kalimantan Timur adalah agar guru dapat memiliki keterampilan membuat proyek pembelajaran IPA jenjang SMP dan sederajat dengan mengintegrasikan bidang Science, Technology, Engineering, Art. dan Mathematics. Pelatihan diselenggarakan selama lima hari, mulai tanggal 22 hingga 26 Juni 2021 dan diikuti oleh 10 guru IPA SMP dan sederajat di Kalimantan Timur. Indikator keberhasilan kegiatan dirumuskan: 1) 80% peserta atau sebanyak 8 peserta hadir dalam pelatihan, 2) terlaksananya seluruh kegiatan pelatihan, 3) 70% peserta atau sebanyak 7 peserta mampu membuat proyek STEAM dan menyusun laporan; serta 4) respon positif dari peserta kegiatan. Instrumen yang digunakan antara lain soal pre-test dan post-test pemahaman pembelajaran berbasis STEAM serta angket respon peserta. Adapun tahapan pelaksanaan kegiatan pelatihan meliputi: 1) Tahap persiapan; 2) Tahap pelaksanaan; 3) Tahap monitoring, evaluasi dan pelaporan. Hasil evaluasi menunjukkan kegiatan pelatihan mencapai seluruh indikator keberhasilan kegiatan yaitu: 1) seluruh peserta yang diundang hadir dalam pelatihan yaitu sebanyak 10 orang, 2) seluruh kegiatan pelatihan dapat terlaksana sesuai jadwal, 3) 80% peserta mampu membuat proyek dan menyusun laporan yaitu sebanyak 8 orang, serta 4) diperoleh respon positif dari peserta kegiatan, hasil angket respon berada pada kategori sangat baik dengan persentase sebesar 95%. The purpose of the STEAM Learning Training for Junior High School Science Teachers in East Kalimantan is to have the skills to create science learning projects by integrating the fields of Science, Technology, Engineering, Art. and Mathematics. The training was held for five days, from 22 to 26 June 2021 and was attended by ten junior high school science teachers in East Kalimantan. The indicators for the success of the activities were formulated: 1) 80% of participants or as many as 8 participants attended the training, 2) the implementation of all training activities, 3) 70% of participants or as many as 7 participants were able to do STEAM projects and compile reports, and 4) positive response from activity participants. The instruments used include pre-test and post-test questions on understanding STEAM-based learning and participant response questionnaires. Implementing the training activities includes 1) Preparation stage; 2) Implementation stage; 3) Monitoring, evaluation and reporting stages. The results of the evaluation show that the training activities achieved all indicators of activity success, namely: 1) all participants invited to attend the training were 10 participants, 2) all training activities were carried out according to schedule, 3) 80% of participants were able to do projects and compile reports, which amounted to 8 participants, and 4) a positive response was obtained from the activity participants, the results of the response questionnaire were in the very good category with a percentage of 95%.