If you see a bunch of old stuff in your Redis instance that you don’t recognize, it’s probably from whichever student had that instance number last semester, and they didn’t empty their trash before they left that course.

Basically: nuke it. You can either systematically DEL the stuff you see when you do KEYS *, or, as a heavier hammer, do the FLUSHDB command. Realize that the FLUSHDB command will irreversibly nuke everything in your current instance, so triple-check that (1) you’re on the correct instance and (2) you really do want to nuke all the stuff. Lmk if you have any questions or doubts.