Circles Resources

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Websites

What Pi Looks Like

A visualization of the many, many known digits of the number π. There's just…so many of them…

Videos

Sesame Street: Geometry of Circles

A Sesame Street video featuring the music of Philip Glass. Some interesting properties of circles show up in the animation. See if you can follow along and describe what's being constructed.

Where Pi Comes From

This is a short animation visualizing where π comes from. No, not the bakery.

Equation of a Circle

Watch this guy derive the equation for a circle from the distance formula.

Constructing a Tangent to a Circle

Put on your hard hat; there's some construction going on here. Today's project: a line tangent to a given circle.

Games and Tools

Lost in the Northern Frontier

In this game, you'll use what is essentially a 2D version of GPS to find a lost astronaut. Circles can save your life, you see.

Sporcle: Circular Definitions

Match the circle-related term to its definition as fast as you can.

Circle Terminology and Practice

These terminology questions are designed to trip you up. Let logic be your walking stick.

Geometry: Working with Circles

You'll know the answers to some of these circle-related questions right away. Others may actually make you think for a few minutes.

Circle Geometry Review

A Jeopardy-style review game that'll make sure you know all the answers…er, questions…when it comes to circles.