In this paper, we describe the development and preliminary assessment of ACORN Physics Tutorials, which are designed to elicit and build on common conceptual resources for understanding physics. We articulate our design principles and instructional commitments and how these bear out in the specifics of one ACORN Physics Tutorial about electric circuits. We describe preliminary results from research on the implementation of the circuits ACORN Physics Tutorials. Namely, we observe students' sensemaking in real time as they complete worksheets; we document shifts in students' performance and use of specific conceptual resources from pre- to postinstruction using ACORN Physics Tutorials; and we show that students generally perceive their ideas to have mattered as they work with their peers on these worksheets. We hope these results can inform instructor decision making about the appropriateness of ACORN Physics Tutorials for their local contexts.