Scheme is nice and syntactically similar to Logo, in the respects of simplicity. Also Scheme offers a very intuitive way of understanding recursion and picking up these type of fundamental concepts in computer science that early on is nothing but good with more good.
UCB Scheme also offers a lot of built in functionality for manipulating sentences, which may make more sense to a 7 year old than constructing polygons and solving number puzzles (not to say that the sky's the limit!).
