Slicing Cylinders

Tom Hickson, University of St. Thomas; Ilyse Resnick, Temple University; and Carol Ormand, SERC, Carleton College
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In this exercise, students identify and draw slices through cylinders and partial cylinders, and use gestures to visualize slicing planes. This practice with visualizing slices through idealized geometric shapes is preparation for visualizing slices through geological features.

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Learning Goals

After successfully completing this exercise, students will be able to sketch slices through cylinders at a variety of angles and will be able to recognize a variety of shapes as slices through cylinders or semi-cylinders. It is my hope that they will be able to transfer that ability to thinking about slices through geologic features, such as cylindrical fossils or semi-cylindrical river channels, as well.

Context for Use

This exercise is designed to be used early on in a course that requires a lot of mental slicing (imagining cross-sections through sedimentary deposits or deformed rocks, for example). I use it as a prelude to an exercise on recognizing channel deposits. While this exercise is likely to be fairly easy for most students, it will allow you to quickly see whether you have any students who struggle with visual penetrative thinking ("mental slicing").

Description and Teaching Materials

Students work through a series of exercises, from multiple choice questions about slices through cylinders to free sketching of cross-sections through idealized "channels." Cylinder slicing exercise (Microsoft Word 2007 (.docx) 4.7MB May19 15)

Teaching Notes and Tips

This exercise was developed as part of a set of exercises to support 3D visualization skills. These exercises had an intended order. Instructors can pick and choose the exercises, but the order we intended was as follows:

  1. Introduction to 3D sketching
  2. Sketching block diagrams
  3. Sketching 3D Ripples and Dunes
  4. Slicing cylinders
  5. Slicing channels
  6. Slicing fruit
  7. Slicing rocks
  8. Slicing fossils


I look over student sketches to see how well they are able to sketch the cross sections.

References and Resources

Using Gesture to Support Spatial Thinking highlights the value of gesture in communicating spatial information. It consists of two short exercises, and can be used in preparation for any other exercise in which students will be asked to use gesture to communicate spatial information.