Lesson objective: Identify equations that require composing a new ten.

This lesson helps to build fluency with deciding when a new ten needs to be composed. Base ten blocks are used here because it supports students in seeing how ten individual cubes are equivalent to a ten rod. This work develops students' understanding that we can add tens with tens and ones with ones and sometimes it is necessary to compose a new ten.

Students engage in Mathematical Practice 6 (Attend to precision) as they trade ten ones for a group of ten. Trading too few or too many ones will result in a wrong answer.

**Key vocabulary:**

**Special materials needed:**

- base ten blocks
- equation sorting cards
- yes/no sorting headline cards (see In-Class Practice)