A couple years ago, we designed a FLL-style challenge with FRC robots, with an L-shaped field (very similar to the hallway in our building, oddly enough

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Anyway, we broke the kids up into two teams (Phobos and Deimos), and the challenge was to go retrieve an object from a box (out of sight, so they needed cameras) and bring it back. We mostly used parts laying around the shop. Whatever we had was fair game.
Obviously, you don't need to have something even remotely similar to what we did, but the whole idea of an off-season "competition" of some kind is a great way to round out whatever curriculum you have set up.