A framework for teaching scientific inquiry in upper secondary chemistry education was constructed in a design research consisting of two research cycles. First, in a pilot study a hypothetical framework was enriched in collaboration with five chemistry teachers. Second, a main study in this community of teachers and researchers was conducted on the process of designing teaching scientific inquiry based on the enriched framework. Also, the enactment by five teachers and 80 students (age 17) of a designed inquiry module on "Diffusion: moving particles" was studied. This resulted in a theoretically and practically founded framework for teaching scientific inquiry, in which an iterative cycle of inquiry for students and a student inquiry community are essential. (Contains 1 table and 2 figures.)