Maximizing Profit: Selling Soup

Mathematical goals

This lesson unit is intended to help you assess how well students are able to solve real-life mathematical problems. In particular, students will develop their abilities in the following areas:

  • Using proportional relationships to solve multistep ratio and percent problems.
  • Drawing inferences about a population from a random sample of data.
  • Making and stating assumptions based on real-life situations.


The lesson unit is structured in the following way:

  • Before the lesson, students attempt the Selling Soup task individually. You review their solutions and formulate questions that will help students to improve their work.
  • At the start of the lesson, students respond individually to the questions set.
  • In groups, students combine their thinking and work together to produce a collaborative solution in the form of a poster.
  • In the same small groups, students evaluate and comment on some sample responses. They evaluate these responses and compare them with their own work.
  • In a whole-class discussion, students explain and compare solution strategies.
  • Finally, students reflect on their work and their learning.

Materials required

  • Each student will need a copy of the task sheet, Selling Soup, pages 1 to 4 of Responses to Martha’s Survey, some plain paper to work on, a copy of the How Did You Work? questionnaire, a mini-whiteboard, pen, and an eraser.
  • Each small group of students will need a sheet of poster paper, a marker, and copies of the Sample Responses to Discuss.
  • Provide calculators for students who choose to use them.
  • There is a projector resource to support whole-class discussion.

Time needed

20 minutes before the lesson and a 120-minute lesson (or two 60-minute lessons). Timings are approximate. Exact timings will depend on the needs of your class.