I've enjoyed salvaging through hole components from old/broken electronics. It won't nessecarily teach you any electronic theory, but you'll begin to pick up on

I've enjoyed salvaging through hole components from old/broken electronics. It won't nessecarily teach you any electronic theory, but you'll begin to pick up on certain patterns of circuit design, especially if you look up IC data sheets as you're doing it. Potentiometers, big electrolytic capacitors, inductor coils, switches, are all easily salvaged and reused. It's a low risk way to get more comfortable with a soldering iron too.