The Effect of Team Based Learning Model on Students' Critical Thinking Skills in Ecosystem

21st century education must be able to develop the students' various skills, one of which is the critical thinking skill. Critical thinking skills are reasonable and comprehensive way of thinking that are used to make decisions. The aim of this study was to determine the effect of Team Based Learning (TBL) models on student critical thinking skills in Ecosystem. The research method used in this study was a Quasi Experimental Design method with pretest post test control group design. There are 60 students on each class selected through simplerandom sampling. The instruments used were 15 items about critical thinking, which have been declared valid and reliable. The result showed that the average critical thinking scores of students increased significantly by using Team Based Learning (TBL) model. The highest gain score in the experiment class on first aspect (Clearness) is in gain score of 0,7 (high). Mean while the smallest increase occurred in control class on aspect accuracy, relevance, breadth and precision in gain score of 0,0 (low). A t-test indicated that TBL students’ critical thinking skills significantly increased (sigvalue. 0.00). The conclusion was that there was an influence on the application of the Team BasedLearning (TBL) model on students’ critical thinking skills in Ecosystem.