Yesterday we posted a link to handwork templates as a means of entertaining your children, yes, but also as a way to keep their math skills sharp.  

"The frilly crenulated forms that you see in corals, and kelps, and sponges and nudibranchs, is a form of geometry known as hyperbolic geometry. And the only way that mathematicians know how to model this structure is with crochet. It happens to be a fact. It's almost impossible to model this structure any other way, and it's almost impossible to do it on computers. So what is this hyperbolic geometry that corals and sea slugs embody?" http://ow.ly/NEOb30mTkUP