ECMs are teacher guides that include supports for teaching strategies and for teacher learning. They are designed to increase teachers’ knowledge in specific instances of instructional decision making by helping them develop more general knowledge that can be applied flexibly in new teaching situations. This allows teachers in PLCs to explore the range of ideas that students teaching the lesson. The ECM prompts teachers to use classroom discussions to have students compare their individual solution bring to the problem prior to strategies to the strategies used by their classmates to solve the problem. In this manner, the teacher learns the mathematical knowledge needed to press student thinking and understanding, and to make the distinction between conceptual and procedural knowledge visible to students. In addition, the teacher is afforded opportunities to explore, discuss, and implement a variety of instructional “best practices” in a safe environment that support student engagement with the mathematical content.
Table 1 (below) provides an example page of a prototype ECM that would accompany a portion a lesson on proportional reasoning. The structure of the ECM is intended to provide a narrative context for the progression of the mathematics. Please note that the left-hand column describes the sequence of the actual task to be used during the student investigation, and provides possible discussion prompts. The middle column offers insights into the mathematics and prompts for teacher reflection. This column provides
explanatory comments about the mathematics, brief questions that press the teacher’s thinking about the underlying mathematics in the task, and explicit connections to important mathematical concepts that are possible extensions from the task. The right-hand column provides samples of student work that press teacher understanding of the mathematics students might uncover during the course of the lesson.