This lesson provides an opportunity to observe the ways in which students make use of structure and repeated reasoning to design a Number Talk. The Warm-up is followed by four Number Talk design activities. In the first activity, students are given three expressions and asked to write the unknown expression. In each of the subsequent activities, one additional expression is unknown. In the last activity, students write all four expressions of a Number Talk.

It is not essential that students complete all four activities. Decide which activities to do, based on how much scaffolding students may need. The lesson may take more than 1 day, especially if students facilitate their Number Talk with other groups.

If students need additional support with the concepts in this lesson, refer back to Unit 3, Sections A and B in the curriculum materials.