This Instructional Activity is a part of the Lesson 11, Unit 7, Grade 7. In this activity, students are given pictures and descriptions of planes cutting prisms and pyramids. Students are asked to draw cross sections freehand but this is not a skill that is required in order for students to be able to describe two-dimensional shapes created from cross sections, which is why this is an optional activity. Some pictures are of a moving plane. Students describe how the cross section changes as the plane moves. If students have access to the digital activity there are applets to explore the cross sections.