PENGARUH MODEL PEMBELAJARAN GUIDED INQUIRY DAN MODIFIED FREE INQUIRY TERHADAP KEMAMPUAN BERPIKIR KRITIS SISWA PADA MATERI PENCEMARAN LINGKUNGAN DI SMA NEGERI 1 KOTAPINANG

This study aims to determine the effect of inquiry based learning model on students’critical thinking skill of the environmental pollution topic at SMA Negeri 1 Kotapinang. The research method used is quasi experiment with sample as much as 3 classes, those are taken by using the technic of cluster random sampling. Guided inquiry based learning model is taught in class X-1, modified free inquiry based learning model is taught in class X-2, and traditional based learning model is taught in class X-3. The instruments are used in this study are critical thinking skill test which form multiple choice. The technique of data analysis used in this study is analysis covariat by using the program of SPSS 23.0 for Windows. The study results showed that there is effect of inquiry based learning model on students’critical thinking skill (F=26.015; P=0.000). Students’ critical thinking skill that were taught by guided inquiry based learning model (75.00 ± 8.701) not different significant with modified free inquiry based learning model (79.03 ± 8.930) (P=0,161), and not different significant with traditional based learning model (70.00 ± 10.142) (P=0,062). But different very significant between modified free inquirybased learning model with traditional (P=0,000). The result of this study is expected from the teachers to apply guided inquiry or modified free inquiry based learning model when they are teaching environmental pollution topic in order to increase students’critical thinking.