This Instructional Activity is a part of the Lesson 17, Unit 6, Grade 7. Remind students of the types of slices taken in Lesson 15: slices parallel to a face and slices perpendicular to a face. This lesson examines slices made parallel and perpendicular to the rectangular base of the pyramid. As with the last lesson, understanding the slices is made easier when students are able to view and handle physical models. Consider using the figures constructed from the nets in the Opening throughout these exercises.