As craptastic as it is looking back, I wanted to give props to something that really got me started in drawing chibi. It's great for kids to get started.
When I was in middle school and had already gotten into the whole anime/manga craze, I found this book at our school's book fair and couldn't pass it up. Katy Coope, How to Draw Manga
I bought it immediately and started drawing from its advice but the section I liked more than anything was the chapter they had on chibi characters, or Super Deformed characters. I drew chibi for hours and hours.
Soon I gree apart from that book and moved onto bigger and better things. But I will ALWAYS remember that book and how it got me my start. It may look pretty bad now, but back then this book was the shit. If you have a struggling child or are struggling at the beginning stages it might be a good thing to pick up.
For more advanced chibi drawing, this is also a good read.