Rote memorization gets a bum rap, but sometimes it can be useful. I’m glad I was made to memorize the times tables up to 12, for example; I can’t remember whether I knew exactly how the process of multiplication worked at the time, but it’s sure handy some 20 years later to have all those sets immediately available at my fingertips.
So what other sets of facts would it be helpful to have memorized? Never mind concepts, necessarily: I’m looking for stuff that can fit on a pack of flashcards. Some ideas:
Major country capitals
Presidents’ terms of office (even if you don’t know anything about a president, it would give a helpful framework if you knew automatically who was in the White House in any given year - would help connect the dots as you learned more history later on)