Forest M. Mims III was a master at using cartoons in his electrical engineering books. Just look at the happy and sad lightbulbs on page 1 of Getting Started in Electronics[1].

Using cartoons a great way to disarm the reader, especially children, into believing the subject matter will be understandable. I don't know if Mims used cartoons to make engineering appeal to children, but it certainly had that affect on me.

[1]http://www.flickriver.com/photos/mightyohm/tags/forrestmmims...