Start like this. You need five people, arranged in a pentagon, and a roll of string or color tape. Take the tape, and pass it two people to your right, unrolling as you go, until you reach the person at the beginning.
This creates a simple star.
Now try scaling up. Instead of five people, try seven. With seven people, you can make two different types of seven-pointed stars. Pass the tape two people the right, and you get one type of star. Pass the tape three people to the right, and you create another.
But try an even number of people, and something different happens. You get back to the person you started with before reaching everyone in the circle.
In one of her videos, Vi Hart, a “mathemusician and virtual reality philosopher,” explains the mathematics that underlies these stars.
What if you tried to make a star with 17, even 19 people, at the vertices? At Atlas Obscura’s Total Eclipse festival in Eastern Oregon this past weekend, we tried. “Both of these are the largest I’ve ever done,” Hart told the audience.