Lesson 8

The purpose of this lesson is for students to understand that 10 ones make a unit called a ten. Students compose and decompose teen numbers with a ten and some ones.

In this lesson, students build on their work from kindergarten where they composed and decomposed teen numbers with ten ones and some more ones. They learn that 10 ones is equivalent to a unit called a ten. In the first activity students count a collection of 16 objects and represent their count. In the second activity, students compose teen numbers with a ten and some ones. This lays the groundwork for a later unit in which students compose and decompose 2-digit numbers into tens and ones.

• Each group of 2 needs a bag of 16 single connecting cubes.

Which students had opportunities to share their representations and thinking during whole-class discussion? How did you select these students?