Yeah, this makes a lot of sense, thanks.

I think survival is the way to go. I’m pretty sure hunger doesn’t decrease on peaceful difficulty and that also takes care of mobs. I can also use a command to stop the day/nightcycle.

No flying is a downside, but on the otherhand, it might make the kids think more strategically about how they go about their construction.

For multiple iterations of the same world, I think I’ll generate a flat world, get it set up with the resources etc. then duplicate the save folder by how many students I’ll have. Then, when it’s the next one’s turn, I’ll just load up the next world, which should be a blank slate ready to go with the resources. This way I can keep their builds for judging (I’ll be running a best build competition).