In previous lessons, students composed and decomposed units to add and subtract within 1,000. Students considered which sums and differences within 100 were more or less difficult for them to find.

In this lesson, students develop fluency with adding and subtracting within 100. In the first activity, students play a new version of Heads Up game to practice fluency. This version is structured differently than the game students played in Section A. For example, students play in groups of 3 and use different recording directions. In the second activity, students choose which center game from previous units to play based on what they know they need to practice. Spinners and cards can be reused if they were saved from previous units or new cards can be printed for the centers and stages recommended for this lesson.

The Cool-down should be completed before the Lesson Synthesis so that students can share their responses during the Lesson Synthesis.