Math Practices

Standard 5: Use appropriate tools strategically.

Standard 6: Attend to precision.

What the Teacher is Doing

Preparation: Have materials available. Students must be able to use rulers to measure to the tenth of an inch. Ensure students can use operations with decimals and/or fractions.

What the Student is Doing


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Students use string and ruler to measure circumference and diameter of circular objects (lid of a jar, clock face, pie plate). Students will divide circumference by diameter, resulting in pi (students will not be informed they are finding pi- that is part of the discovery process).

Students will recognize that pi is an irrational number- it cannot be measured precisely.

The discovery process shows a relationship between circumference, diameter, and pi.

Example of Rich Tasks

  • Students research how cultures have used pi from ancient to modern civilizations.
  • Students research the method developed by Archimedes using inscribed and circumscribed circles.