If you have a roaster you can cook the pasta ahead of time to al dente. Boil water in the roaster at the school (I assume you will have electricity ) and immerse the noodles in the water for a few minutes as you need it. In the second roaster you can heat the sauce. This way both the noodles and the sauce will be hot when you serve them.
You can always put the sauce on the bottom, put the cooked noodles on top and just mix it when you're ready to serve it. We have a local spaghetti joint that does a lot of carry out orders and that's how they do it in the plastic tubs we get.