The Communication in Science Inquiry Project (CISIP) investigated the impact of writing intensive, inquiry based professional development on high school teachersâ€™ science content knowledge of Energy in Systems. In particular, we investigated whether different forms of assessment provided different information about the depth of teacher knowledge. We developed a two-tier Energy Test, linked to both national and state science standards, which was administered both before and after science teacher particip-ation in 23 hours of professional development on energy in biological and societal systems. Our study found that we were successful in relaying content knowledge to the teachers. When we analyzed misconceptions in distracter choices and written responses on the same test, however, we found we were successful in some areas, but not in others. The application of knowledge gained about energy in systems through writing scientific explanations was the least successful of all.