There are other authors who would be good to stimulate the imagination and lead up to Norton. The Mr. Bass and the Mushroom Planet series (can't remember the authors name) is a favorite with 3rd graders. Heinlien is good for beginners too. And of course there is C.S. Lewis's Narnia series beginning with "The Lion the Witch and the Wardrobe". Not SF, but very good, as a said at stimulating imagination and the "what if" bump, which we are all born with!

May I suggest the best way to introduce your son to SF is to read it yourself? Isaac Asimov had some excellent books for young people that he revised shortly before he died. All about boys going in to space and playing around on Mars, that sort of thing.

Andre's "Forerunner" books (in any order) gave me a very early love of lore and learning. The Zacathans and their search for knowledge in all the ancient civilizations made me so hungry to do some archeology myself! Not to mention it intoduces the scientific method in a very palatable format.

Also ask your local childrens' librarian. They really have their pulse on what are current and past favorites that kids love.

Lucky you, and lucky son, to be imbarking on this wonderful reading together time!

Erin