Read more about the purpose of the MAP Classroom Challenges

Solving Real-Life Problems: Baseball Jerseys

Mathematical goals

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

  • Interpret a situation and represent the variables mathematically.
  • Select appropriate mathematical methods to use.
  • Explore the effects of systematically varying the constraints.
  • Interpret and evaluate the data generated and identify the break-even point, checking it for confirmation.
  • Communicate their reasoning clearly.


The lesson unit is structured in the following way:

  • Before the lesson students attempt the Baseball Jerseys task individually. You then review their responses and formulate questions for them to consider when thinking about how they could improve their work.
  • At the start of the lesson, students think individually about the questions posed.
  • Next, students work in small groups to combine their thinking and work together to produce a collaborative solution to the Baseball Jerseys task, in the form of a poster.
  • In the same small groups, students evaluate and comment on sample responses, identifying the strengths and weaknesses in these responses and comparing them with their own work.
  • In a whole-class discussion students compare and evaluate the strategies they have seen and used.
  • In a follow-up lesson, students spend ten minutes reflecting on their work and what they have learned.

Materials required

  • Each individual student will need a copy of the assessment task: Baseball Jerseys, some plain paper, a mini-whiteboard, a pen, an eraser, and a copy of the questionnaire How Did You Work? Provide calculators if requested.
  • Each small group of students will need a large sheet of paper, some felt tipped pens, and copies of Sample Responses to Discuss.
  • Graph paper should be kept in reserve and used only when requested.
  • There is a projector resource to support whole-class discussions.

Time needed

15 minutes before the lesson, a 70-minute lesson and 10 minutes in a follow-up lesson (or for homework). Timings given are only approximate. Exact timings will depend on the needs of the class. 

Mathematical Practices

This lesson involves a range of mathematical practices from the standards, with emphasis on:

Mathematical Content

This lesson asks students to select and apply mathematical content from across the grades, including the content standards:


Lesson (complete)

Projector Resources

A draft Brief Guide for teachers and administrators (PDF) is now available, and is recommended for anybody using the MAP Classroom Challenges for the first time.

We have assigned lessons to grades based on the Common Core State Standards for Mathematical Content. During this transition period, you should use your judgement as to where they fit in your current course.

The Beta versions of the MAP Lesson Units may be distributed, unmodified, under the Creative Commons Attribution, Non-commercial, No Derivatives License 3.0. All other rights reserved. Please send any enquiries about commercial use or derived works to

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