This paper offers an account of, and findings from, an approach to designing and evaluating an instructional sequence set in the context of Newton's third law. The design of the sequence draws upon conceptual change theory and the concept of the "bridging analog" is extended to introduce the notion of a "bridging representation" Attention is also given in the instructional design to the proposed social interactions between teacher and students as the teaching and learning activities are played out or "stage" in the classroom. A range of instruments is used to measure the extent of student learning, and evidence is presented to indicate that the designed sequence leads to enhanced learning gains when compared to those achieved with an equivalent group of students. Although set in the context of teaching and learning about mechanics a number of general points are made in relation to both instructional design and perspectives on conceptual change.