Designing a 3D Product in 2D: A Sports Bag

Mathematical goals

This lesson unit is intended to help you assess how well students are able to:

  • Recognize and use common 2D representations of 3D objects.
  • Identify and use the appropriate formula for finding the circumference of a circle.


The lesson unit is structured in the following way:

  • Before the lesson, students attempt the Designing a Sports Bag task individually. You review their work and formulate questions that will help students to improve their solutions.
  • At the start of the lesson, students respond individually to the questions set. Then in groups, they combine their thinking and work together to produce a joint solution in the form of a poster.
  • In the same small groups, students evaluate and comment on sample responses. They identify the strengths and mistakes in these responses and compare them with their own work.
  • In a whole-class discussion, students explain and compare the strategies they have seen and used.
  • Finally, students reflect on their work and their learning.

Materials required

  • Each student will need a copy of Designing a Sports Bag, some plain paper, a mini-whiteboard, a pen, and an eraser.
  • Each small group of students will need a new copy of Designing a Sports Bag, some poster paper, a marker, and copies of the Sample Responses to Discuss. Provide calculators, rules, and squared paper for students who request them. An optional Formula Sheet is available for use as required.

Time needed

25 minutes before the lesson, a 95-minute lesson (or two 50-minute lessons), and 15 minutes in a follow-up lesson. Timings are approximate. Exact timings will depend on the needs of your class.