Unit 1, Lesson 3
Slicing Solids
Integrated Math 3
Preparation
Lesson Narrative
Students analyze cross-sections, or the intersections between planes and solids, by slicing three-dimensional objects. Next, they identify three-dimensional solids given parallel cross-sectional slices. In addition, they revisit solid geometry vocabulary terms from earlier grades: sphere, prism, cylinder, cone, pyramid, and faces.
Students use spatial visualization to make sense of three-dimensional figures and their cross-sections throughout the lesson (MP1).
- Generate multiple cross-sections of three-dimensional figures.
- Identify the three-dimensional shape resulting from combining a set of cross-sections.
- Let’s analyze cross-sections by slicing three-dimensional solids.
- I can identify the three-dimensional shape that generates a set of cross-sections.
- I can visualize and draw multiple cross-sections of a three-dimensional figure.
Required Preparation
Activity 1
Obtain several cylindrical food items to cut with a plastic knife.
Activity 2
For the digital version of the activity, acquire devices that can run the applet. If using the paper-and-pencil version, prepare various solids from clay or play dough, such as cubes, spheres, cones, and cylinders. Each group of 3–4 students should have access to a three-dimensional solid to analyze.
Alternatively, consider getting food items with interesting cross-sections or getting three-dimensional foam solids from a craft store. If so, get plastic knives to slice the solids.
cross-section
A cross-section is the two-dimensional figure formed by intersecting a solid with a plane.
These diagrams show that the shape of the cross-section depends on how the plane intersects the solid.
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