Lesson 12

The purpose of this lesson is for students to compose and decompose 10 in multiple ways and find the number that makes 10 when added to a given number.

In a previous lesson, students matched equations to compositions and decompositions of 10. In the first activity, students show many different compositions and decompositions of 10 with red and yellow counters. Students may know 5 and 5 as a way to compose and decompose 10, because this structure is highlighted when using fingers and 10-frames. In this lesson, students develop familiarity with other ways to compose 10. In the second activity, students determine how many counters are needed to fill a 10-frame.

• Each group of 2 needs 1 cup and 10 two-color counters.

• Gather materials from: 
  • Shake and Spill, Stages 1–3
  • Counting Collections, Stage 1
  • Roll and Add, Stages 1 and 2

Reflect on your experience with the Which One Doesn’t Belong warm-up in the curriculum. What moves or questions have improved the learning for each or your students during this routine? What improvements would you make next time?