Items needed:

  1. A thin paper plate that folds easily.

  2. A piece of string about a foot long.

  3. A ruler with the centimeter scale on it (This makes measurements easier)

  4. A pen or marker to write on the plate and mark your string.

Before beginning the activity, remember, radian measure of an angle = arc length/radius.


  1. Fold the plate in half. Then fold it again to get 4 equal sections.

  2. Use centimeters to measure the diameter of the circle.

  3. Use the string to measure the arc length of half of the circle.

  4. Use the formula above. Did you get something close to 3.14? If not, try again being careful to take all measurements as accurately as possible.

  5. Now repeat the first 4 steps with one fourth of the circle.