Lesson objective: Compose and decompose angles.

This lesson helps to build fluency with composing and decomposing angles. Pattern blocks are used here because it highlights the composition of a cirlce with multiple angles. This work develops students' understanding that angles can be composed and decomposed.

Students engage in Mathematical Practice 4 (model with mathematics) as they use pattern blocks to decompose angles by starting off with concrete examples. Students see that the measures of all of the angles at a point, with no overlaps or gaps, add up to 360°, and they use this fact to find the measure of the pattern blocks’ angles.

**Key vocabulary:**

- acute
- angle
- compose
- decompose
- degrees
- obtuse
- right
- straight angle

**Special materials needed:**