More than 100 science and mathematics teachers have participated in the ASU Math and Science Teaching Fellows program for summers in 2007-2010 at Arizona State University. The goal of the program was to expose the teachers to the real world of science and help them transfer the experience into the classroom. The teachers spend the mornings in small groups in assigned research laboratories and afternoons in whole group interactive sessions. During the afternoon sessions the teachers worked on a poster presentation and a classroom unit integrating the research experience. The present study focuses on the impact of the research experiences on the teachers’ classrooms and the differences between a larger and longer program (37 teachers for 5 weeks in 2009) and a smaller and shorter program (8 teachers for 4 weeks in 2010). The lesson plans were coded based on a rubric. The posters were coded using qualitative analysis software. The scores on the lesson plans and the frequency of codes on transfer to classroom were higher in 2010 compared to those in 2009. The results indicate that the research experience program had a better impact on transfer to school curriculum with a smaller cohort of teachers. This implies that future research experience programs should be designed for smaller groups of teachers.