My father or uncle had a 50-in-one kit from their childhood and showed it to me when I was a little boy, from at least the early 70's/80's. I was amazed that I can make an LED blink, make a light detector, and listen to sounds on the crystal earpiece included. I got discouraged when it required 20 whole connections to make an AM radio transmitter, how I had no clue.
Took electronics in highschool, maybe it was a little fast paced and I hadn't gotten much out of it. Found the workbook years later and was just captivated by it all, the formulas, what you can do with just a few simple concepts.