I didn't identify them from the pics, but I remember apron hoops. Boy, y'all got off easy making aprons in home ec. We made sheath dresses with darts and an 18 inch zipper down the back and were hand hemmed! I did learn a lot from that project though.
I don't think they are bakelite, but you can test them by holding them under hot water (running is best as I remember) and then quickly smelling them. Real bakelite usually gives off a chemical odor. There are some more definitive tests that you can do, but that's the easy one.