Research on conceptual change indicates that not only children, but also teachers have incomplete understanding or misconceptions on science concepts. This mixed methods study was concerned with in-service teachers' understanding of four earth and space science concepts taught in elementary school: reason for seasons, phases of the moon, rock cycle, and earthquakes. The participants were 29 second year graduate students in an Urban Master Program at a southeastern American university. The data sources were: an open-ended survey given before and after participation in six hands-on learning stations on earth science concepts and teacher reflections in dialogue journals while participating in the stations. Rubrics were used to score answers to each survey question. Findings indicate that in-service teachers have low conceptual understanding of the earth and space science concepts taught in elementary school. Secondly, paired samples t-tests results showed that participation in hands-on stations on these science concepts changed teachers' understandings of these topics. Finally, dialogue journals contained useful positive reflections, negative reflections, suggestions, and comments on preference to teach the activities in the future. This study has implications for teacher preparation programs, staff development, and conceptual change practices at elementary schools. (Contains 4 tables.)