The people in Hawai'i that put out "The Philosophy of Liberty" have some kids' materials geared for home schoolers. Also, if the 10 yr old is a good reader, Peter Schiff's book (or even the original version by his dad, Irwin) can be fun. Two of my study hall students always want to borrow my copy to read. And they're about 11-12 yrs old (7th grade).
My dealer says that an inexpensive way to get into coin collecting is to do a "type" collection. They can pick a year famous for something and get one of each type of coin minted that year.
One year, I gave my older niece an electronics educational set where she could learn all about electricity and wiring while setting up increasingly complex systems.