A style that differs from the style a student already gets in school generally helps learners in supplementary programs like Khan Academy.
A really great example of a superb mathematics textbook by a top mathematician, all with hand-drawn diagrams, is Geometry: Euclid and Beyond by Robin Hartshorne.
The author explains his rationale for having hand-drawn rather than computer-generated geometry diagrams, discusses why he wrote the book as he did. I love this book as a remarkably accessible book on some very deep mathematics, with wonderfully challenging problems. I think Khan Academy video lectures work for some of the same reasons that Hartshorne's approach in Euclid: Geometry and Beyond works, and I hope that Salman Khan and his collaborators eventually get to advanced geometry like that in Hartshorne's book in the Khan Academy course list.
A really great example of a superb mathematics textbook by a top mathematician, all with hand-drawn diagrams, is Geometry: Euclid and Beyond by Robin Hartshorne.
http://www.amazon.com/Geometry-Euclid-Beyond-Robin-Hartshorn...
The author explains his rationale for having hand-drawn rather than computer-generated geometry diagrams, discusses why he wrote the book as he did. I love this book as a remarkably accessible book on some very deep mathematics, with wonderfully challenging problems. I think Khan Academy video lectures work for some of the same reasons that Hartshorne's approach in Euclid: Geometry and Beyond works, and I hope that Salman Khan and his collaborators eventually get to advanced geometry like that in Hartshorne's book in the Khan Academy course list.