Yes, a Karen vote, 100%. I barely made it past the first paragraph without rolling my eyes. Let's call a spade a spade, the OP has a transgression against "rap" music and that got him/her all riled up...because one of the parodies used that beat. A very innocent beat at that. Keyword, no lyrics, just the beat with parody voice over. If the beat would have been Elvis, OP likely would have moved on. OP is trying to convince us that it's all about the laziness of the teacher using YouTube, blah. Its not, its your bias against rap music. Therefore, you lose credibility for me to take this serious.
It takes 5 seconds to find that video too, and it's got 5 million views with tons of comments about social studies teachers using this. Again, you hate rap music so much you can't even handle the beats being used, and you stereotype an entire genre to boot.
Clearly the teacher is trying to give the kids a "fun" project to do, so maybe they might pay attention vs. traditonal text book assignment. I can likely guarantee this isn't the core teaching method for this teacher. Cut him/her a break.