Penelitian ini bertujuan menghasilkan perangkat pembelajaran guided discovery yang layak digunakan untuk meningkatkan hasil belajar siswa pada materi termokimia. Kelayakan perangkat pembelajaran dinilai berdasarkan validitas, kepraktisan dan keefektifan. Penelitian ini merupakan penelitian kuantitatif dengan menggunakan desain penelitian pengembangan (R&D). Perangkat pembelajaran diujicobakan pada siswa kelas XI MIA 2, XI MIA 3, dan XI MIA 4 di SMA Muhammadiyah 3 Surabaya tahun ajaran 2018/2019 dengan rancangan one group pretest-posttest design. Instrumen penelitian meliputi lembar validasi, observasi, tes, dan angket. Data yang diperoleh dianalisis secara deskriptif. Hasil penelitian menunjukkan bahwa: (a) validitas perangkat pembelajaran yang dikembangkan termasuk dalam kategori sangat valid, (b) kepraktisan perangkat pembelajaran berupa keterlaksanaan RPP pada tiga kelas memperoleh kategori sangat baik dan aktivitas siswa pada ketiga kelas telah menunjukkan bahwa pembelajaran berpusat pada siswa, (c) keefektifan perangkat pembelajaran yang dikembangkan berupa tes hasil belajar yang memperoleh nilai rata-rata di kelas XI MIA 2 sebesar 79,8, kelas XI MIA 3 sebesar 88, sedangkan kelas XI MIA 4 yakni sebesar 83 dan persentase respon siswa di ketiga kelas mengenai perangkat pembelajaran yang dikembangkan menunjukkan kategori sangat baik. Berdasarkan hasil analisis dan pembahasan, disimpulkan bahwa perangkat pembelajaran berorientasi guided discovery yang dikembangkan valid, praktis, dan efektif untuk meningkatkan hasil belajar peserta didik melalui materi termokimia

The aim of this research is to produce a proper guided discovery learning instruments to improve learning outcomes in thermochemistry material. The properness of learning instruments were assessed based on validity, practicality and effectivity. This was a quantitative research that used research and development design (R&D). Learning instruments were tested on students of XI MIA 2, XI MIA 3, and XI MIA 4 class Senior High School of Muhammadiyah 3, Surabaya in academic year 2018/2019 with one group pretest-posttest design. The research instruments include validation, observation, test, and questionnaire sheets. Data were analyzed descriptively. The results showed that: (a) validity of learning instruments developed was included in a very valid category, (b) practicality of learning instruments in the form of implementation of lesson plans in three classes that obtain very good categories and student activities in all three classes have shown that student-centered learning, (c) effectivity of the learning instruments developed in the form of learning outcomes tests that obtain an average score in MIA XI 2 class of 79.8, MIA XI 3 class of 88, while the XI MIA 4 class is equal to 83 and the percentage of student responses in the three classes regarding learning tools developed shown that in a very good category. Based on the results of the analysis and discussion, it was concluded that the guided discovery learning tool was valid, practical, and effective to improve students’ learning outcomes through thermochemical material.