Skip to main content


8th Grade Math - Representing Constant Rate of Change

Clip 4/17: Rate of Change: Pre-Lesson Part 2B


Antoinette Villarin and colleague Cecilio Dimas prepare for her lesson by discussing the formative assessment she’d given her students prior to the documented lesson, and what she noticed in analyzing her students’ work. Antoinette shares that her students have not yet demonstrated mastery of moving from a graphical representation to an equation. While they are familiar with the concept of proportionality, they don’t yet grasp the idea of a constant rate of change. Antoinette and Cecilio discuss how their analysis led to a selection of particular strategies to engage students with the concept of a constant rate of change — and restating their understanding of a careful reading of a graph. Antoinette describes her rationale for using a “turn and talk” strategy to require her students to be explicit in their mathematical discourse.

Teacher Commentary

This is a good example of implementing a strategy that Cecilio suggested. I would often tell my kids to turn and talk to their partner. He mentioned, "Have you ever thought about giving them a strategy where you ask them to turn and talk with a purpose and a product?" I tried it and just that one change of how I framed what I was asking students to do and how it included a purpose and product, changed the whole dynamic and energy in all my classes and their discourse. I feel like Cecilio knows a lot. I trust him and I respect him as an educator. I remember him from [prior professional development] and now when we do these summer institutes he's presenting, he has lots of knowledge. I think there's just a lot of trust, a lot of respect, and he really knows what he's talking about.