What do they mean...
This is, of course, what happens in other schools all the time. You know, the ones where all the students turn up every day, on time (unless they were delayed helping old ladies across the road), in clean uniforms, bright of eye and shining of face. They ask for extra homework, and never run in the corridors.
Unfortunately, in real life arguments are things in which to get bogged down, entrenched, and attritional. If you want the class to resemble the Western Front in 1916 even more than it does already, start a discussion.
Watch the glints of hatred appearing in the eyes of former friends as they slug it out over the relative merits of republic and monarchy, or whether Hannibal should have brought more elephants. As the volume rises with the heat of debate, and the cries of "That's stupid, it's obvious that Wordsworth only wrote poetry to sublimate his incestuous feelings for his sister" become more threatening, it is vital for the teacher to be near an exit, and possibly a fire extinguisher.
Thank goodness, today's schools (sorry, learning environments) have a method of ending conflicts unavailable in early 20th-century Flanders: the bell. As our discourse-enriched charges hurtle out into the playground, we may reflect on what wisdom was gained in the lesson. Never, ever, try that again.