When I was in junior high school we had a monthly mail order kit from American Basic Science. I made things like an amplidier, radio receiver, ham radio transmitter. It cost $5 a month for a year, much of the pay from my paper route.

http://www.quickreference.info/small-business-stories/americ...

An equivalent today might be a the add on kits for Raspberry Pi or Arduino. Plus the high school robot competition clubs.

Must have worked because I later attended MIT ;-)