[sukilot]

Formal logic is taught in Mathematical Logic class (intermediate, optional) or Discrete math (intro/intermediate, often not taken)

Geometry class in high school sometimes teaches some of it.

Computer science Binary logic teaches some of (De Morgan's laws)

Outside of New Math of the 1970s, it is a glaring omission from the curriculum.

Even enriched classes like Art of Problem Solving that put heavy emphasis on proofs, do not teach formal logic.

[cubefox]

To be fair, I think some people just quickly and intuitively "get" what's expected from them when doing proofs, without any formal introduction. But for others (like me) it is very much helpful to at least list the basic natural deduction inference rules, and to do a bunch of exercises where they have to use these rules explicitly. Otherwise they are floating in thin air, with only a hazy idea of what a "valid logical step" even is.