The effects of science learning unit using problem–based learning about local sugarcane on 9th grade students’ critical thinking ability

The purpose of this research was to study the effectiveness of the science learning unit using problem–based learning on local sugarcane to the learning critical thinking ability which were four critical thinking abilities; 1)problem defining 2)decision making 3)identify hypothesis and 4)making conclusion. The samples used in this study consisted of thirty 9th grade students in one classroom in the second semester of the 2017 academic year. The research design used in this study was one group pre-test post-test with sixteen periods for implementation. Students’ critical thinking ability was collected by using the critical thinking ability test. The critical thinking ability test was developed by researcher. It was 40 multiple choice questions with 10 situations. The reliability of the test was 0.873, the difficulty of the test ranged from 0.22-0.78, and the discrimination power of the test ranged from 0.2-0.68. The test was administered two times at the beginning of the semester, and after learning science learning unit using problem–based learning on local sugarcane. The data were statistically analyzed by mean, standard deviation and a t-test for a dependent sample. The results found that the critical thinking ability mean score after learning with the science learning unit using problem–based learning was higher than those been before learning at statiscally significant level and mean score after learning was higher than the cutting score was also significantly higher at a level of .05.