Lesson Study makes teacher collaboration concrete and focuses on specific goal (Wang-Iverson, 2005). In the context of schools with internship students, there is a collaboration of teachers and internship students in the schools. The objective of this research was to survey collaborative approaches between teachers and internship students in mentioned school under the Project of Teaching Professional Development by Lesson Study and Open Approach (Inprasitha, 2010). A different context which it causes variety approaches to collaboration in lesson Study to be conducted. The target group is 66 lesson study teams included teachers and internship students in 21 schools by teaching mathematics 2011 school year. Data were collected by questionnaire and interview. They were analyzed and presented by descriptive analysis. The results showed that in collaboratively design research lesson, most of lesson study teams were run by internship students who designed research lesson first then kept it to discuss with the teachers in lesson study teams. Followed by internship students design research lesson first then kept it to present with the teachers in lesson study team. During collaboratively observing the research lesson that there are three approaches: Internship Students organized the learning activities observed by the teacher that 1) teachers observed by observing and Recording that not to say anything; 2) teachers observed by observing and recording that teachers facilitates and encourage students by asking questions; 3) teachers observed by observing and helped the internship students in classroom management by warning the students and advise internship students. The period of collaboratively reflection on teaching practice, most of lesson study teams were reflecting followed in the school's schedule.