I love books that help me answer the questions my toddler asks. She asks questions that my scientist mind wants to answer with richness and depth. And I will someday. But I know these answers are not age-appropriate and she won't understand them. So I hunt out fun books that help me explain in honest yet simplistic terms to her the answers she wants. Our latest discovery is When the Wind Stops to explain why it gets dark at night. It is a bit complicated for her sense of space but I think with repeated readings, the ideas will sink in.