A cycle for validating a learning progression illustrated with an example from the concept of function

A learning progression, or trajectory, describes the evolution of student thinking from early conceptions to target understanding within a particular domain. As complex theory development, it requires conceptual and empirical support. In earlier work, we proposed cycle for validation progression with four steps: 1) Theory Development, 2) Examination Empirical Recovery, 3) Comparison Competing Models, 4) Evaluation Instructional Efficacy. group experts met discuss application sciences design, use, classroom assessment. Learning progressions, trajectories, how they can support assessment were main focuses. Revisions suggested. We describe adapted illustrate first third has been applied towards concept function.