Teachers' content knowledge and their skill in teaching concepts are key research findings for effective teachers. Collaborative learning is also found to be a way to improve teachers' subject-matter and pedagogical knowledge. Taking this into account, the practicum course in the second semester of the academic year 2013 at Udon Thani Rajabhat University was designed to prepare professionals in teaching for 4th year Thai student teachers. There were six stages of learning that the students had undergone in order to develop these professional skills. In this research, the following steps were followed. First, student teachers' misconceptions in specific science contents were diagnosed and discussed. Second, the students were made to participate in learning activities using those concepts. Third, a peer review of science lesson plans was analysed, focussing on an appropriate teaching method to teach specific science content and learning tasks. Peer discussions and reflections were conducted from Stages 4 through 6: collaborative lesson preparation; peer observation of teaching; and reflection. It was found that the student teachers held common misconceptions in science as revealed in the research findings. The preparation process was effective in that it gave a sense of ownership to student teachers working in collaboration with their peers to plan and implement instructional activities.