Not that I think my advice will be taken, but here it goes.
I don't know about the rest of the world, but at my school in america, after school was very different than it is in Korea. At my school we had a reason for going, a goal. In speech and debate every week we would compete with other schools. with history club we had quiz bowls with other schools. with art club we would compete in art competition. and guess what sports clubs did.
my point is, after school in korea is mostly just a time sink parents drop their kids off at so they are not out on the streets. You have a chance to do whatever you want, I suggest thinking back to how after school was when you were in high school and try recreating that. have a reason for them to show up, a goal to work towards.
chances are you cant have them compete with other schools, so best to get creative.
I highly recommend not doing a debate club, the kids will hate it.
Preferably something that will be mostly speaking, and require a minimum of planning.
way to do your job. odd to ask for suggestion when you don't want to work.
have them write stories or poetry to present, speech competition, movie competitions. goals yo, goals.
How often do you meet them?
I will teach them twice a week. The class will be an hour long
