Get the class ready and hand it over to the students before the leader comes. Listen to the class again and ask a few questions. Let the whole class print the books on the blackboard and try to find one with a slightly better academic record. It doesn't matter if there are mistakes, because everyone likes to make such mistakes. We should talk more about ways to avoid these mistakes. One or two minutes before class, give students some homework about what they have learned in this class, and then class can be over. The leader will leave and then comment on the open class. These are all my experiences.