Active learning is a procees whereby Critical thinking is an intellectually thinking process in which the thinker uses reflective and critical thought. This paper discusses on how the teacher could solve the problem in teaching and learning activities. This study also described how teacher had facilitated the students to develop their critical thinking skills. The action research study was conducted at grade XI students for the acid base topic. There were 40 students all together, but only 39 students complete all the tasks. The indicator used were the quality of interaction and the mastery increasing was measured on pre-test and post test.  The Indicators used for critical thinking skills were the students’ ability in 1) delivering  explanation, 2) analyzing  an argument, 3) making a conclusion, and 4) giving a result of consideration. Data were analyzed into qualitative descriptive. Results showed: 80% of the students polled agreed and 20% stated they strongly agree with the learning invites students to present the results of their study orally. The students need for communication among students although the school hours and shown there were 80% of students strongly agreed and 20% agreed with the discussion. The students have used the ability of thinking, they had developed the delivering explanation, analysis, summarize and consider the results.

Key words: teacher problem, action research, critical thinking, students’ability