>Do people still teach about the Maginot Line in schools?

No.

There are plenty of other opportunities to teach the value of making your adversary (be that adversary man made or natural) work every step of the way and they are missed too. Nobody (for large values of "nobody") gets taught about the value of layered or redundant systems until college and those that do get taught it in college usually only touch on it in their mandatory ethics elective.

FWIW I named the last firewall I configured "Little Maginot".