This article compares the experiences of two elementary teachers, each of whom attended a traditional workshop on the development of conclusions within science notebooks. One teacher continued to expand her learning on this topic by participating in a lesson study group; the other did not. Through a qualitative case study, I explored the impact on teachers’ beliefs and practices and student outcomes as a result of participating in lesson study. Data from teacher interviews, video of classroom lessons, and student work were collected and analyzed. This study suggested that participation in lesson study may positively affect a teacher's beliefs and practices related to using science notebooks and, in turn, student outcomes.