I have been looking for read-alouds that can educate, and not just entertain, the girls. I thought we would try The Cat in Numberland, by Ivar Ekeland. It claims to be a novel which teaches the concept of infinity. We have never discussed the concept of infinity, so I thought this may be a fun, educational read.
The book made the girls think about numbers in different ways. There is a whole chapter about the number ZERO. Some characters think it is a number, some do not. Another chapter discusses the concept of the hotel being "full" but yet also having the ability to house more numbers.
I think the girls learned the concept of infinity from this book. They still, a week later, mention infinity frequently. They challenge each other to "count to infinity." Catherine asked me if she started counting now and kept counting until she was an old lady if she would get all the way to infinity.
So, the book did it's job: it introduced the girls to a new concept. Bravo!