Calculating Pi

Type: Investigation

Theme: Engineering

Grades: 5, 6, 7, 8, 9, 10

Learning Target: Students will use a physical model to determine the value of pi algebraically.


Please collaborate with a partner (2 students only). If you would like to work alone, please contact your teacher.

This math investigation is all about precision and accuracy. Calculate the value of the number pi (π) by measuring the circumference and diameter of a circle. Solve algebraically.

  1. Estimate the value for π.
    1. Make a plan. How will you find or draw a precise circle? How will you measure it properly? Plan must be writtens. Include steps. Bulleted list is OK. Be sure to include details. Sketches are not required, but advised.
    2. Gather materials.
    3. Construct or measure your circle. Measure both the circumference and the radius.
    4. Solve for π out to four decimal places. Older students can estimate their expected error. Please do not alter your values to adjust your estimation for π.
  2. Briefly research why π is important to an aspect of engineering or architecture. Please write two to three paragraphs and cite your sources.
  3. Submission: Word document containing the following (you are not required to create a PowerPoint).
    1. Your name(s)
    2. Your plan (if possible include a photo of you and/or your partner making measurements)
    3. Your value for π, please include your measurements
    4. Your research about using π in architecture or engineering

Ideas for Measurements

  • The larger the circle the better.
  • Make very accurate measurements.
  • Use string and chalk outside on a flat surface.
  • Use string and dry erase marker on a window.
  • Use a large circular object.
  • Work small with a compass, protractor, magnifying glass, and a very sharp pencil!


Exit Ticket
CCSS Math Practice
  • I can attend to precision.
NGSS Crosscutting Concepts
  • Scale, Proportion, and Quantity