My son mentioned this issue to my granddaughters and showed them a computer video. I had no idea this debate was raging in the world of mathematics and geometry.

You can find, virtually anywhere, the debate about tau (τ) versus pi. Tau is actually 2 π.

The debate results from the strange phenomenon that has happened over the history of mathematics.

The Greeks and maybe some earlier Babylonians discovered that the radius of the circle was related to the circumference of the circle by an irrational number that they called π.

Over the millennia since then we have developed concepts of harmonics and sine waves and a whole range of mathematical and physical phenomenon that use 2π. You will find it in the Fourier transform, Planck's constant and almost any other physics equation.

It turns out that tau not π is the number that seems to define our universe.

While I'm very opinionated and have a surplus of opinions, I now have an additional opinion that we should be using tau instead of π.

Here is a wonderful 10 min. video that I hope will convince you that we should be teaching tau in addition to pi.