Hi ,
I have a book called Practical Percussion by Kevin Edwards which is very good, and I have to say you've chosen the perfect age to start him off as I didnt get started untill I was 11 and im turninng 15 in may so good luck for him.
Thanks,
Pembo
Heres a link:
Kevin Edwards: Practical Percussion (CD Edition) at Musicroom.com - Tuition Books