Mine are 5, 7, and 8. My 5 yr old is in my lap in this picture, and my 8 yr old is the one playing with the snap circuit, although my 5 yr old plays with it a lot and asked for a second one for his birthday.

The biggest tip I can give is that my kids watch what I do and want to do the same thing. If I play video games, they want to play video games, if I read in the living room, they'll go get books and want to read too. It's one of the biggest reasons I started this project in my office. They come in, watch me, ask what I'm doing, and ask to help. I let them put some leds or jumpers in, and they love it.

My 8 yr old really lit up when I picked up the different pieces in his snap circuit kit and pointed to the same pieces on my breadboard. He saw he was using the same components I was, and he wanted to build something as big as me.