This paper reports on a design-based implementation study of the use of a diagnostic classroom assessment tool framed on learning trajectories (LTs) for middle grades mathematics, where teachers and students are provided immediate data on students' progress along LTs. The study answers the question: "How can one characterize the challenges…

Dynamic Assessment (DA) derives from Vygotsky's (1987) insight that the use of mediation, attuned to learner needs, enables learners to perform beyond their current level of functioning, thereby providing insights into emerging capabilities. The instructional quality of mediation means that this process simultaneously creates possibilities for…