Abstract
Changes in teaching practice have not kept pace with the changes envisioned in numerous
reform documents. In this paper, we present the results of a study of an experienced
secondary teacher who taught a sequence of modelling tasks designed to investigate
exponential growth and decay. Our results suggest that changes occurred in her practice
along three dimensions: her role in listening and questioning, a new emphasis on student
explanation and justification, and a more fluid view of the representations of the concepts.
Helen Doerr & K. Jamie King