This Instructional Activity is a part of the Lesson 25, Unit 6, Grade 7. Students use the formula to determine the volume of a right prism. Before students learned that a polygonal base of a given right prism can be decomposed into triangular and rectangular regions that are bases of a set of right prisms that have heights equal to the height of the given right prism. By extension, the volume of any right prism can be found by multiplying the area of its base times the height of the prism.