Why? When I was that age, I would tear apart all of the electronics in my possession trying to figure out how they worked. I never could figure it out, until much, much later. Not because I couldn't have understood it, but because I didn't have anyone to help guide me with regards to electronics.

edit:

I would have killed for someone to have gotten me something like http://www.amazon.com/Snap-Circuits-SC-300-Electronics-Disco... which is listed as appropriate for age 8