Training pre-service teachers requires, among other things, content knowledge, pedagogical skills and pedagogical content knowledge. Teacher preparation programs have little, if any spare time to add more courses/activities to their program. However, I argue in this paper that we, as educators, must enhance the amount of physics education research in our pre-service physics teacher training programs. In this study, I analyze the results of two different types of exposure to physics education research (PER) from two different groups of pre-service physics teachers in our masters of arts and teaching program. The preliminary results show, for example that the PER helped the pre-service teachers increase their understanding of student thought processes while they solved problems. Physics teachers must have this type of ability to be successful in the classroom.