Informed by decades of research and standards-based policies, there has been a growing demand for high-quality teaching and learning in mathematics and science classrooms. Achieving these ambitious goals will not be easy; students' opportunities for learning as shaped by the tasks they are assigned will matter the most. The purpose of this article…

The transition from student to expert professional can be accelerated when a trajectory for change is plotted and made visible to learners. Trajectories or paths toward expertise are domain specific and must first be documented and then used within instructional contexts to promote knowledge transitions. This article describes how models of…