Most modern tech I can explain in terms of what it does, what it's like to live with. I think this is how I'd explain TV to someone from 1920, but it would be just as easy as explaining it to someone from 1820:
"It's a sheet of glass, and moving pictures with sounds appear on it."
"How does it work?"
"I don't know. It involves several dozen separate inventions, of which I understand perhaps three individual ones well enough to discuss."
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Of course, to really blow the minds of people from 1920, you can either show them anything related to space travel (especially the Apollo missions, but also GPS); or tell them about basically any organ transplant; or show them a 3D printer (you know Bakelite? We found better plastics, and we made a machine that can, without ongoing intervention, use that make any shaped structure we ask it to… and those machines can also do metal, and yes that includes the engines of those spaceships we showed you earlier. Also houses).
"It's a sheet of glass, and moving pictures with sounds appear on it."
"How does it work?"
"I don't know. It involves several dozen separate inventions, of which I understand perhaps three individual ones well enough to discuss."
--
Of course, to really blow the minds of people from 1920, you can either show them anything related to space travel (especially the Apollo missions, but also GPS); or tell them about basically any organ transplant; or show them a 3D printer (you know Bakelite? We found better plastics, and we made a machine that can, without ongoing intervention, use that make any shaped structure we ask it to… and those machines can also do metal, and yes that includes the engines of those spaceships we showed you earlier. Also houses).