Providing meals on site can help your festival run more smoothly. If meals are not provided on site, extra time needs to be built into the schedule to allow folks to get to and from restaurants. In some cases this is the only option. Meals may be provided by the school cafeteria staff, a caterer, a group of parents or some other organization. Regardless of who provides this service, do not assume that they know best how to serve a festival meal.
Generally there is not much time for a meal. Therefore the speed with which a meal can be served becomes critical. The number of serving lines can be critical. In a self serve situation try having lines on both sides of each serving table. Place plates at the beginning of the serving table and napkins, utensils, drinks & condiments at the end or at another location entirely. Another option is to have the food distributed ahead of time at the dining tables. This can work at breakfast sometimes or at a meal of pizza.
Yet another option would be to preset the tables and have parents or some organization serve the meals to the tables. This can be done family style with large serving bowls & dishes.
Keep meals simple and inexpensive. The host should break-even on meals. This is not the place to make your profits. People have to eat. Remember teenagers have big appetites. Try to offer variety at each meal. Include nutritious vegetarian options. This does not mean just leaving out the meat. Substitute bean or dairy products. Include nutritious diabetic options. Consider possible religious restrictions if there is a holy day involved.