We have 2 of these books in our home library. There are a good investment but try one first from the library. My DS10 has kept his interest in these for about 4 years.
How Come? by Kathy Wollard
How Come? Planet earth by Kathy Wollard
How Come? In the Neighborhood by Kathy Wollard
How Come? Every Kid's Science Questions Explained
There is also an ultimate book thread here. You might find something. Also look at mindware.com for ideas.
http://www.how-come.net/ Check out this website. You can ask a question and if it's published in the newspaper they will send you a book. We sent in 5 question. Wish us luck.
