Lesson objective: Identify the shape of the two-dimensional face created when a three-dimensional figure is sliced.

This lesson helps to build spatial reasoning by slicing three-dimensional figures. Drawings are used here because they represent both three-dimensional figures and their two-dimensional faces. This work develops students' understanding that slicing three-dimensional figures creates new faces of two smaller figures.

Students engage in Mathematical Practice 4 (model with mathematics) as they apply their undersatnding of three-dimensional figures to identify the shape of the new face.

**Key vocabulary:**

- face
- three-dimensional figure
- two-dimensional figure
- slice