<![CDATA[The purpose of this research was to find out the influence of discovery learning model to critical thinking skill and students learning activity on immune system subject matter. The sample were students of IX IPA1 and IPA2 SMAN 16 Bandar Lampung. The design of this research was pretest posttest non equivalent. The quantitative data were critical thinking skill that were obtained from pretest and posttest which analyzed by using t-test and U-test with signification level of 5%. Learning activity data and students perception were analyzed descriptively. The results showed that N-gain of critical thinking skill on experiment class was 45,63 which was higher than control class was 29,36. Learning activity on experiment class was 75% which was higher than control class was 59,19%. Therefore, discovery learning model gave significantly influence in improvement of critical thinking skill and students learning activity on immune system subject matter.Penelitian ini bertujuan untuk mengetahui pengaruh model discovery learning terhadap keterampilan berpikir kritis dan aktivitas belajar siswa pada materi sistem pertahanan tubuh. Sampel penelitian adalah siswa kelas IX IPA1 dan IPA2 SMAN 16 Bandar Lampung. Desain penelitian pretest posttest non equivalent. Data kuantitatif berupa keterampilan berpikir kritis yang diperoleh dari pretest dan posttest dan dianalisis menggunakan uji-t dan U dengan taraf signifikansi 5%. Data aktivitas belajar dan tanggapan siswa dianalisis secara deskriptif. Hasil penelitian menunjukkan N-gain keterampilan berpikir kritis kelas eksperimen (45,63) lebih tinggi dibandingkan kelas kontrol (29,36). Aktivitas belajar kelas eksperimen (75%) lebih tinggi dibandingkan kelas kontrol (59,19%). Sehingga, model discovery learning berpengaruh signifikan terhadap peningkatan keterampilan berpikir kritis dan aktivitas belajar siswa pada materi sistem pertahanan tubuh.Kata kunci: aktivitas belajar, berpikir kritis, discovery learning]]>
