Lesson objective: Extend understanding of three-dimensional shaped figures from rectangular prisms to non-rectangular prisms.

Students bring prior knowledge of three-dimensional figures from CCSS.5.MD.C.3.B. This prior knowledge is extended to faces of non-rectangular prisms as students identify the shapes needed to create nets of several prisms. A conceptual challenge students may encounter is keeping the correct proportions of the faces to correctly match the prism.

The concept is developed through work with nets and two-dimensional figures, which show the two-dimensional shape of the faces of three-dimensional figures and distinguish between bases and other faces.

This work helps students deepen their understanding of equivalence because the two-dimensional figure in the net is congruent to the face of the three-dimensional figure. Bases of prisms are always congruent. The length of side of a face, is congruent to the side of the face with which it shares an edge.

Students engage in Mathematical Practice 7 (Look for and make use of structure) as they identify the shapes of faces of prisms and identify the bases of the prisms.

**Key vocabulary:**

- base
- congruent
- face
- net
- parallel
- prism
- surface area
- three-dimensional figure
- two-dimensional figure