OMG this was fabulous, thanks everyone! I just ILL a whole bunch of these, although my library does not have either the murderous math or uncle alberts, and those sound great. Might have to get them. I am very excited about the hawking books especially, my DS will eat it up, he is more science than math so I am always looking for math concepts just for some balance! He liked the sir cumference books, although they beat you over the head a bit. If yours like puzzles, we definitely loved the graeme base books, especially enigma, and 11th hour. And not exactly a children's book, it's a mystery but with great pictures, the clock without a face.