But some professors say they have significantly changed their teaching practices to accommodate the students. During quizzes, Dr. St. Pierre now requires everyone to leave their books at the front of the classroom to prevent cheating, a precaution not taken during any of his two decades at Delaware. And participation counts less, so as not to sink the grades of foreign students. In the past, he required members of the class to give two or three presentations during the semester. Now he might ask them to give one. “I’ve had American students saying they don’t understand what’s being said in the presentations,” he says. “It’s painful.