I really liked the way that Iverson built up concepts in his [Arithmetic (PDF)](http://www.jsoftware.com/books/pdf/arithmetic.pdf http://www.jsoftware.com/books

I really liked the way that Iverson built up concepts in his [Arithmetic (PDF)](http://www.jsoftware.com/books/pdf/arithmetic.pdf http://www.jsoftware.com/books/pdf/arithmetic.pdf) manual for J. I found it very intuitive and useful even if you never plan to use the language. There are others at the site like his manual for Exploring Math and one for Calculus as well.