Playful side of geometry??????

"The playful side of arithmetic" is a statement that people my not believe is true. It means that there are things that you can do to make math fun. Rocks may not sound like the funnest thing in the world, but you can use it for fun when you use it in math. Using straws could be one way to make triangles.
Calculus means pebble in Latin.  This has to do with the article because it uses rocks as examples in it.
You can make a pattern that consists of the numbers 1-10 using ten rows like the example below. The example is from an article by Steven Strogatz