Once upon a time, back in the days of "stone knives and bearskins", Radio Shack made a series of kits for the budding electronic engineer known as 50-in-1 kits. (You could get bigger sets that promised up to 200 different things you could make.) The kit would be a box with a nice wood frame and a cardboard top that had bunch of different electronic components on it like resistors, capacitors, diodes and one or two transistors. Each of the components would be tied to a little spring that you would bend back to insert hook-up wire into. No soldering and it was a breeze to take apart. The kit would start off with something simple showing how circuits are made using a switch, a light bulb and a battery. It would end up showing you how to make a tunable AM radio or oscillator.
I had one of these kits when I was a kid. My sister and I split the cost of buying one and I ended up monopolizing the use of it. It was at this point when I was a kid, I knew I was going into some line of electronics. I loved following the directions and learning the art and also trying to design my own buy taking there design and "bending" it so the oscillator would run a little faster or slower or pick up a different spectrum of radio to listen to.
Radio Shack has long since stooped producing these kits. I think Radio Shack is missing an opportunity here as they are very visibly sponsoring things like the Maker Faire and other MAKE Magazine Projects efforts. So where Radio Shack, dropped the ball on this a company called Elenco has put out a similar 50-in-1 kit. Amazon sells them for less than $25 each. Cheap! Having a 9 year old son that has a technical bent, meant we had to have one. It was a great time bonding with him on how to build a simple circuit and creating something more complex like an AM radio. It is well worth the $20 investment. (Actually, I have to credit David Diaz for buying it for my son at Fry's.)
Elenco has a number of pretty cool electronics kits that you can buy and put together with your kids. Their model "FUN-875" is a radio controlled race car that took my son and I a couple of evenings to put together. Once we did, we had a pretty nice little car that ends up being pretty sturdy too.
So, three cheers to Elenco for making electronics a little more accessible to kids again.