to tessellate...

...is not naughty; tho it certainly sounds like something that you'd flirtatiously engage in with a rather intimate partner.

It actually is the fitting together of repeated shapes to form a solid pattern. Triangles, squares, and hexagons fit nice and neat with their own shapes.

However, octagons don't fit with other octagons. They do fit with squares in the spaces left as other octagons don't have the right angles to fit into the spaces, without leaving gaps.

So, I've decided to make an afghan of large hexagons. I've already used a rose skein, which made about 20 rounds, a nice size. The finished afghan will look something like this: