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Fruit Pi

Happy Pi Day! Lets's celebrate the amazing relationship between the circumference and diameter of circles using some fruit from the fridge. A great way to get kids thinking, learning and doing hands on Math at home. This lesson can be modified for Pre-K through High School through how much helping parents are doing.

What is Pi, besides one of the best desserts you can make with fresh picked Hudson Valley Apples? Pi is the ratio between the circumference and diameter of circles. It is approximately 3.14 which is why it is celebrated on March 14th, but in reality it is a decimal that never repeats and never ends. This irrational number looks like this at the start 3.1415926535 8979323846 2643383279 5028841971 6939937510 5820974944 5923078164 0628620899 8628034825 3421170679 ... Since this number is a bit crazy, mathematicians gave it its own special symbol and name.

1st find some circular fruit in the fridge. There just has to be a circle when you slice it. We chose an apple. of course, orange and grape. You can go really big here and use a melon, but a blueberry wold be small and hard to work with.

Other materials you will need:

  • knife

  • cutting board

  • parchment paper

  • pen

  • ruler

  • calculator (or practice some decimal division)

  • Optional (printed Hurds hand out and pencil)

Cut circular slices from the fruit and then in each one make a little notch or line.

Use the ruler to make lines on the parchment that will be used to measure the circumference (outer edge) of the fruit slice.

Mark a starting point on your line. Place your fruit slice upright like a wheel with the notch on the very top. Carefully roll the fruit along the line until the notch is back at the top. Make a mark on the line where the bottom of the slice is touching. That length is your circumference.

Take your fruit slice and stamp it along the line to see that the line is about 3 and a little bit more. This is the special relationship for every circle the circumference is about 3 times the diameter.

For little kids the math can stop here and the creativity can begin with this simple printable Pi Coloring page.

Measure the diameter of the slice. You want to move your ruler to go straight through the center of the slice and measure the widest distance. Then measure the length the fruit sliced rolled aka circumference. Divide the circumference by the diameter to see how close to the number Pi you get. There will be some error here because our measurements can only be just so precise. That's totally OK the important thing is seeing that there is a relationship between the circumference and diameter. This discovery long ago is what led mathematicians to find the "exact" value.

Elementary students can measure in centimeters and use a calculator to divide.

Middle school students can measure in centimeters and divide without a calculator OR measure and inches and practice their fraction skills.

Take this lesson outside with a piece of chalk and measure how far your bike wheel rolls.

High school students should be creating a plan all on their own on how they will measure the circumference and diameter. Let the creativity fly. Will they choose to use a piece of string or tape. Will they know so much about pi already they will choose to measure the diameter and calculate the circumference for you? Will they suggest to not even cut the apple and to use a caliper to measure? It is all dependent on your child's abilities and unique prior experiences.

Print and use our handout if you would like something to help your children organize there work.

We highly recommend using some NY Apples to make a pie. No Pi Day is really complete without a piece of fruit pie. If you are looking for a recipe. Check out Aunt Ange's Apple Pie.

We love your feedback. Please let us know how the Fruit Pi lesson went and the Apple Pie tasted!

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Address 2187 State Route 32 Modena, NY 12548

Tel 845-883-7825 

Fax 845-883-6300

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New York Apple Picking Farm