Teachers' ability to elicit and build on students' mathematical thinking during instruction is critical in order to support students' mathematical growth. An emerging hypothesis in the field is that the construct of a "learning trajectory" (LT) has the potential to support teachers in making sense of and using student…

This article describes one teacher's efforts at creating a differentiated mathematics program in her multi-age first- and second-grade classroom. The author describes challenges encountered and successes met in this process, as well as the structures she uses to meet a variety of student abilities, including open-ended problem-solving tasks,…