Children are often taught about circuits at school right from grade one. Even before that, there are the parents who keep repeating (at least a few times everyday) not to poke objects into the sockets. I know that kids find it to be a thrill when they actually get to experience the inner workings and reasoning behind such things, and learning about circuits is no exception. By encouraging hands on education, we are laying a solid 3D foundation of independent analytic skills and a sound base for engineering and physics.
Here are a few fun ways to reinforce the concept of circuits at home with your child: