One science book that I love, love, love is If You Decide to Go to the Moon by By Faith McNulty. It's the story of a little boy who is pretending to go to the moon. The book gives such great facts at the end of the story about the moon. Plus WONDERFUL illustrations by Steven Kellogg. And it can easily tie into a writing activity- "If I decided to go to the moon I would bring..."
Be sure to add you favorite science book to the linky party over at Teaching Blog Addicts!