This study explores how an Inquiry-Based Demonstration Classroom (IBDC) professional development program affects the extended inquiry instruction of secondary science teachers and how teachers view their extended inquiry practice while involved in the IBDC professional development program. To assess the impact of the program on participants' practice, each participant was observed enacting extended inquiry lessons. The observations of the inquiry lessons were recorded on the Extended Inquiry Observational Rubric (EIOR), then analyzed for changes in eight categories using a dependent t test. To supplement observational data, participants were interviewed throughout the year and asked to provide a metaphor that describes their instructional role while engaged in extended inquiry lessons. This study analyzes demonstration classrooms and provides additional information on the changes that secondary science teachers experience in their inquiry instruction as they participate in a professional development program that contains a demonstration classroom component. (Contains 16 references.) (DDR)