frogs, snakes, eagles.
Here's a paper which you could [unclear] --
designed by a mathematician at Harvard in 1928,
Arthur Stone,
documented by Martin Gardner in many of his many books.
But this is great fun for children.
They all study about the food chain.
The insects are eaten by the frogs; the frogs are eaten by the snakes;
the snakes are eaten by the eagles.
And this can be, if you had a whole photocopy paper --
A4 size paper --
you could be in a municipal school, you could be in a government school --
a paper, a scale and a pencil -- no glue, no scissors.
In three minutes, you just fold this up.
And what you could use it for is just limited by your imagination.
If you take a smaller paper, you make a smaller flexagon.
With a bigger one, you make a bigger one.
Now this is a pencil with a few slots over here.
And you put a little fan here.
And this is a hundred-year-old toy.
There have been six major research papers on this.