Use ofcase study method in Life Studies courses is important since it is an elementto make students become active. Case studies are provided as a rehearsal of theproblems to get encountered in life. Therefore, in this study quality ofteachers’ use of case study method is examined. The aim of the study is todetermine to what extent teacher trainings based on case studies are effectivein life science courses. For this purpose, action research as one of thequalitative research designs was used. The study consisted of seven teachers workingat public and private schools. Data collection tools in the study are theobservation forms and teacher diaries. In the study, 84 course hours of lessonsinstructed by teachers before and after teacher training were observed. Then,the teacher diaries were examined to analyze their thoughts on their process.At the end of the process, the examination of observations and teachers’ diariesreveal that cognitive questions teachers ask decreased while empathetic andmoral questions increased. Moreover, after the teacher training, quality andquantity of activities used to promote case studies are increased. As a result,it is determined that after teacher training, quality of teachers’ use of casestudy method is increased.