Teach Pi Using Pie

What better way to teach the basic mathematical terms associated with pi than to use a pie? Check out the terms, activities, and discussion points below to help your homeschooler grasp the basics of this mathematical concept. When you’re finished with the lesson, sit down and enjoy a scrumptious slice of pie together!

Items needed:
Pie
Yarn
Scissors
Knife
Toothpick
Yardstick

Radius measures the length of a straight line that starts at the center of a circle and extends to the edge.

1. Insert a toothpick in the center of the pie for reference.

2. Using a knife, lightly draw a radial line on the surface of the pie.

3. Place a piece of yarn on top of the line you drew, cutting it free from the skein at the edge of the pie.

4. Lay the piece of yarn flush against a yardstick to measure its length. This is the radius of your circle.

Diameter measures the length of a straight line that runs from one side of a circle to the other and crosses directly through the center. It is twice the length of the radius, which means you can use the equation d = 2r to calculate it (d = diameter; r = radius).

1. Calculate the diameter of your circle using the equation d = 2r.

2. Using the knife, lightly extend the radial line across the entire surface of the pie.

3. Check your work in step one by placing a new piece of yarn along the line that extends from one side of the pie to the other, cutting it free from the skein at the edge of the pie.

4. Lay the piece of yarn flush against a yardstick to measure its length. This is the diameter of your circle, which should match the number you calculated in step one.

Circumference measures the distance around a circle.

1. Start by predicting how long the circumference of the circle will measure.

2. Place a new piece of yarn around the edge of the pie and use a scissors to cut the piece free from the skein where the two ends meet.

3. Lay the piece of yarn flush against a yardstick to measure its length.

4. Discuss how your student’s prediction compares to the actual circumference of the circle.

Pi is the ratio of a circle’s circumference to its diameter. The number is irrational, meaning that it goes on forever without repeating, and has an approximate value of 3.14159. It can be calculated with the following equation: Pi = C/d (C = circumference; d = diameter).

Plug the numbers you recorded for circumference and diameter into the equation above to see how accurate your measurements are. The result should equal the value of pi (approximately 3.14).

Source: Julie Meyers Pron