Beginning this month, a high school in Colorado will stop letting ninth- and 10-graders leave campus for lunch. At issue, officials say, is the large number of students coming back late from lunch or not coming back at all. Foodservices director Sandi Vanhoutean said she expects school nutrition professionals will adjust to preparing the right quantities of food as more students stay on campus. "Right now the cooks have (quantities) down to a fine science," she said. "There will be some adjustment, but once we observe (purchasing patterns), it'll run like clockwork.