Do 14 year olds in the USA know what "gerund" means?

I didn't know terms like that in England in the 2000s, though I picked them up from learning other foreign languages later.

I have heard university professors complain that they can say, simply, "rephrase the paper into the active voice" to a student from <anywhere else>, but many British students don't know what that means.

England now teaches more grammar, but it is not much use generalizing from individual experiences of a particular state/country in a particular decade.