There used to be an educational concept of making exams really tough and find out what students didn't know but might should have been taught as an aside. Since, at least the mid 1970s, this concept changed to testing what students do know and has been taught as part of the core elements in the subjects.
Those eighth grade exam questions seem to belong to the "let's find out what they don't know" category. I presume that the concept was that students were all expected to know the core elements and it was only the peripheral knowledge that could separate their abilities.
