Horizon - 1970s stylee
I was aged 9 or 10, and learned enough about quarks and particle physics to scare the bejesus out of my science teacher at school (who just about knew about photons).
I knew about strangness and charm, and the weird up and down nature of spin.
Where did I learn so much.
The Saturday afternoon repeat of Horizon.
The next week, I learned about the role Lucy played in redefining our ideas of the timescale of human evolution - being much older than we previously thought. By then I learned not to discuss this at school.
Nowadays, it's hard to tell if "Moments of Wonder" is parodying BBC science, or actually just a summary.