This study looked at a life science course that was offered at and taught by education staff of a large informal science institution (ISI) located in the Midwest. The curriculum, materials, and agendas for the course were developed by education staff and complemented a permanent life science exhibition. The researcher developed a content test based on the course instructional objectives and lessons provided by education staff. In addition, all participating elementary and middle school teachers (n = 62) were asked to complete an evaluation at the end of each day's session. This included several questions that required participants to reflect upon the content presented throughout the course of the day, focusing on their satisfaction and effectiveness of instruction. Overall, teacher responses on the daily and final evaluations for both courses were extremely positive. However, after participating in the ISI course, teachers' gains in science content knowledge were not as strong as they had perceived. The findings described here can assist developers of informal science professional development for elementary and middle school teachers that desire to incorporate inquiry, pedagogy, and science content into their teacher learning experiences.