I was 16 and learning FORTRAN at school. I was a lazy bum at that time (well, that stayed ;-), didn't really prepare, and at the final exam, the teacher asked me in what order the program is executed. Not knowing any better I replied "a value is calculated when the rest of the code needs it" (like in regular math that we did a lot at the time too). She said "not correct, it executes in the order it is written".

-- I doubt she knew anything about functional programming back then.

-- It took me 40+ years to get to the universe where this answer was not completely laughable.

-- And meanwhile what 16 y.o. kids were doing at the time, 6 y.o ones are capable of doing now.