Big Ideas:
Cross-sections formed from horizontal or vertical cut in a rectangular prism are the same as the bases of the three-dimensional figure.
Horizontal cross-sections made from a rectangular pyramid will result in rectangles similar to the base.
Cross-sections formed by vertical cuts to a rectangular pyramid will vary based on where the cut is made.
Students have worked with the volume and surface area of three-dimensional figures in both 6th and 7th grade. The focus of this lesson is to get students to visualize the cross-sections that can be formed in both rectangular prisms and pyramids when sliced both vertically and horizontally. Students will discover that the cross-section from vertical and horizontal cuts to a rectangular prism will be equal to the face parallel from the slice. Students will also discover that different patterns occur when slicing right rectangular pyramids.
Vocabulary: Cross-section, horizontal, vertical, two-dimensional, three-dimensional, parallel, perpendicular, prism, pyramid, apex
Special Materials:
Clay, floss, plastic knives
Lesson plan