Well in defense of the GP, the "planes can observably fly upside down" point (and its close cousin the "flat wing cross sections can fly too" point) is a good one, this pokes holes in the usual two-dimensional "the air goes faster on top" themed explanation that omits any discussion of vortex shedding/third-dimensional effects.
Oh, to be quite honest, I loved trolling my high school teachers with "your explanation fails, here is a real world airfoil, please explain it" and I would draw a symmetrical airfoil or - for extra trolling - a trapezoid one. (At that point I had already flown solo)
But the same I found myself unable to pass by someone pushing "flat plane at an angle".
Fortunately the exam questions that involved lift in high school were simple enough they didn't trigger "you're wrong and the textbook is wrong" response XD
Fortunately my exams were open ended not "fill in the circle in answer sheet" so worst case I'd have written a more complete answer and fought it out.
Worrying about having to fight against "answer key" is part of why only one person (and only on a lark) took computer science on Matura exam in my class - which was CS-math-physics focused one
