One of my favorite things about what Tessalation! has done is give adults with an interest and love of mathematics a book to teach their children about a mathematical concept.
The math isn't in-your-face in Tessalation!, but kids should leave the experience knowing what a tessellation is and, possibly, being able to identify it in the world.
On his blog The Math Less Traveled, Brent Yorgey writes about using the book as a jumping off point for creating tessellations.
Read the full post on The Math Less Traveled here.