I'd recommend something interactive instead of a book (if you can find it), since you said he learns quickly through application.
Introductory programming books don't have much to do with reading level. They (should) be based on functional programming principles and require solid understanding of mathematical principles.
That's why, for now, I'd recommend something that helps him build many small projects through examples.
Introductory programming books don't have much to do with reading level. They (should) be based on functional programming principles and require solid understanding of mathematical principles.
That's why, for now, I'd recommend something that helps him build many small projects through examples.