Slice of Life


This is a Level 3 Geometry activity from the Figure It Out Series. 

A PDF of the student activity is included.

Achievement Objectives
GM3-3: Classify plane shapes and prisms by their spatial features.
GM3-4: Represent objects with drawings and models.
Student Activity


Click on the image to enlarge it. Click again to close. Download PDF (194 KB)

Specific Learning Outcomes
  • Predict the shape formed when three-dimensional objects are 'sliced'.
Required Resource Materials
  • Plasticine or play dough
  • A knife
  • FIO, Level 3, Geometry, Slce of Life, pages 16-17

Predicting results is an important part of this activity.

The angle that the cut is made on will affect the shape of the section. For example, a cut that is at right angles to the axis will give a circle as the cross section of a cone and a cylinder.

These right-angled cuts are much easier to predict than those that are slanted. When a slanted cut is used, the section is very much influenced by how and where the cut is made. A cut through a circle-based cone at a slant will give an ellipse as a section.

A parabola is formed by cutting through a circle-based cone parallel to a sloping side.

Examples of a parabola shape are:

  • the path followed by a ball in flight
  • the shape of wires supporting a suspension bridge.

Answers to Activity

1-3.  Practical activities

4. The sections should look like this:

5. Practical activity

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Level Three