String and scissors are all you need to find pi all around you.

Viscous liquids create a mesmerizing light display.

Try a new tilt on eclipses.

Make dendritic diversions and bodacious branches.

Test how well your brain can see patterns.

Imperfect alignment can lead to interesting patterns.

Surprisingly, a flat panel rolls smoothly on non-circular rollers.

Use straight lines to learn about circles.

Randomly toss some toothpicks, with pi as your reward.

Substitute coins for radiation.

Create graceful loops and spirals by drawing on a spinning disk.

Square wheels roll smoothly on a round road.