Easy As Pie

Mathematics

Students will practice problem-solving thinking about geometry.

What You Need

What to Do

  1. Draw a circle on the board. Ask students if they can see how to divide the circle into six equal pieces using three straight cuts.
  2. Explain that it is possible to cut a pie into four, five, six, or seven pieces using three straight cuts (the pieces will not be of equal size).
  3. Divide the class into groups of three or four. Hand out the Slice the Pie! worksheets. Have the groups work together to fill out the worksheets.
  4. When the groups have had time to complete the worksheets, tell them that it is also possible to divide a pie into eight pieces by using three straight cuts. Challenge them to come up with a solution. (If the groups are stymied, you can hint that in order to cut a pie into eight pieces with three straight cuts, they would need to rearrange the pieces after the second cut.)
  5. Have the groups share their solutions. (To cut a pie into eight pieces using three straight cuts, cut the pie in half with one cut. Cut the pie in quarters with the second cut. Stack the four pieces, one on top of the other, and cut through all four with the third cut.)