Sampling and Estimating: How Many Jellybeans

Mathematical goals

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

  • Model a situation mathematically, justifying any assumptions made.
  • Estimate unknown values/missing information when solving a problem.
  • Calculate volumes of three-dimensional objects.
  • Use an appropriate sampling method to draw conclusions about a population.


  • Before the lesson, students attempt the Jellybeans task individually. You then assess their responses and formulate questions that will prompt students to review their work.
  • At the start of the lesson, students think individually about their responses to the questions set.
  • Next, students work in small groups to combine their thinking and work together to produce a collaborative solution to the Jellybeans 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 each approach and comparing them with their own work.
  • In a whole-class discussion students compare and evaluate the methods they have seen and used.
  • In a follow-up lesson, students reflect on their work and what they have learned.

Materials required

  • Each student will need a copy the assessment task: Jellybeans (printed in color, if possible), a copy of the questionnaire How Did You Work? and some plain paper to work on.

Calculators should be made available on request.

  • Each small group will need a large sheet of paper and copies of Sample Responses to Discuss.
  • There is a projector resource to support whole-class discussions.

Time needed

20 minutes before the lesson for the assessment task, a 100-minute lesson (or split into two shorter lessons), and 15 minutes in a follow-up lesson (or for homework). Timings given are only approximate. Exact timings will depend on the needs of the class.

Lesson Type

Mathematical Practices

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

Mathematical Content Standards

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