I certainly didn’t get “might not have any metal at all” from her answer - just “isn’t ever entirely metal”. I guess that includes “might not have any metal”, but also includes a whole lot of other things.
Either way - I think whiteboard or projector screen are about the only things I can think of at this point.
Yeah, projector screens aren’t especially rare in homes. I’ve owned four in my life. Actually, I guess five if you count the one that went with my parents old slide projector. That’s why I picked whiteboard first… they seem rarer in homes, although offhand I can think of several in homes that, at least pre-Covid, I visited enough to know they had whiteboards.
I basically can’t think of anything (including whiteboard) where I don’t take issue with at least one of the answers. But whiteboard seems closest to working.
Yes!
Perfect reasoning.
I have to say, that while I have been in a room with a smart board that hadn’t been turned on, I’ve never actually seen one being used, and I wouldn’t in a million years say that a white board uses electricity.
For that matter, neither does a water fountain. Y’all forget that I’m old. And water fountains that chill the water are fairly new.
You have to go pretty far down the wikipedia page to find a photo of a water fountain that uses electricity.
I mean, now that you bring it up, yeah, some water fountains use electricity, but I probably would have answered “no” to that question if the answer were a water fountain, just because that’s not my mental image of a water fountain. (And maybe come back an hour later and said “some do”)
The water faucet on my kitchen sink has an electric eye and uses electricity, but if you asked me “does a water faucet use electricity” I’d say “no”, because that’s peripheral to the function.
A 15 second Google search says they’ve been around since the 1950s. That doesn’t seem especially new to me but YMMV.
I guess we have a small (maybe 3’ x 2’ - ish) white board - but I don’t think I’ve ever knowingly been in a house that has a full sized white board in it.
Cheap whiteboard are made of pressboard with plastic or cheap wooden rims. They usually have metal components, but not always.
The only question I felt awkward about was whether they are common in homes. I know a lot of homes with a little one on the fridge or next to the door, that’s used as a household message board. But my best guess is that that’s not too common.
I actually have a full size white board in the basement. But it used to belong to Google. (or some other big company)
I can believe they were invented in the 50s. I can assure you they weren’t common in the 60s or the 70s. And hey, if you walk around NYC today, the parks all have drinking fountains, and those are just plumbed, not wired. Much like the photo of a “typical drinking fountain” in wikipedia. 
Anyway, good timing, as I need to run.
I see them in kitchens and entryways. One relative uses two giant calendar whiteboards to track activities for all five kids and two grownups. Several other friends have them. I suppose probably fewer than 30%, but they don’t seem especially rare.
In college literally everyone had them on the outside of their dorm room doors, but I guess those aren’t really households. I’m guessing the advent of college students with cell phones and texting plans may have eliminated that. College was… a few years ago for me.
Google tells me that 22% of employed people work for some level of government so I suppose maybe it’s reasonable to assume that a similar level of whiteboards are government property. I’m not sure how the white collar / blue collar breakdown compares but with the number of government-run schools from pre-school through university, I suspect that it’s somewhat higher than 22% but possibly not up to 30%. Close enough that I would have put some sort of caveat on the public property thing, but
Hmm, they were common enough in the 1970s that my elementary school (built in the 1920s) had them. Because by 1980 the one in the kindergarten classroom had stopped working and was dispensing hot water. Not ambient temperature… HOT. The teacher joked about making coffee with it.
It was hot enough that she was willing to let the kindergartners venture down to the second grade hallway when we wanted a drink. That one had very cold water.
So there was enough time prior to September 1980 for it to be installed, work for a while, and then stop working.
Come to think of it, the ones in the preschool at church were cooled too. That was in the 1970s. I think they must have been pretty common at least by the late 1970s. Which… isn’t very new.
I’m certainly not claiming it’s rare for drinking fountains to cool water today. Just that I wouldn’t say “it uses electricity”. If I thought hard I might say that it can use electricity. But it’s neither central for the thing to work, nor is it by any means universal today, and since I never saw one that used electricity until I was an adult (and only in “special” places, like airports for a while after that) it’s not in my “default” image of the thing.
I don’t understand your question about “typically public property”. Surely you don’t think half of all white boards are owned by the public? (“in most cases; usually”). Nor that it is somehow characteristic of a white board to be public property. That seemed like a really straightforward “no”.
Ok, I will try to remember to say “commonly” rather than “typically”, if we are interpreting “typically” to mean at least 50%.
I have no idea how water fountains work…