Discover PI

My goal of teaching math is to "discover" math and not "memorize math".How many of you have heard of Pi? Not PIE as in food, I mean the mathematical Pi :-)
Let's begin:

How many of you know what a circle is ?  It has a radius ( R), Diameter ( D ) and Circumference ( C ).  Simple, right?:


Now what is circumference and how do we calculate it? Circumference is basically the length of the circle.

Calculating Circumference :

Draw a perfect circle on piece of paper. Take a thread and place it around the circle. ( Use tape or thumbtacks to hold the thread intact). Now measure the thread length on a ruler. Genius!! You just found the circumference of a circle. ( let's say its called C1 with diameter D1) While you pat yourself, imagine you have measure a large, giant circle's circumference ( think of a truck tire). You can't easily measure it using our thread experiment, can you?

Now here is when math kicks in.


  1. Repeat  your circle experiment again with different size of the circle. 
  2. Measure the circumference and call it C2 with diameter D2. 
  3. Do simple division :
  •  C1/D1 and 
  •  C2/D2. 

What do you get ? You will notice repeatedly it comes to 3.13 or 3.14.

If you can give a symbol to this pattern, it will be called, wait for it.....Pi...tada....Pi= 3.14.

Now you can write a simple equation :

  • C/D= Pi


You can change the Circumference equation to

  • C= D * Pi. 



So when someone asks you the circumference of a circle next time, just measure the diameter of the circle and tell them the circumference. Go on and impress the world with your math discovery.





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