How do you manage a disruptive classroom?
Prevention does most of the work. Clear routines, an engaging task and a well planned start reduce disruption before it begins.
I establish expectations early and rehearse them, for entry, transitions and group work. I use non verbal cues, proximity and names rather than shouting, and I give positive attention to students who are doing the right thing.
If disruption continues I use the least intrusive intervention first: a look, a quiet word, moving seats, then a private conversation. I keep the correction about the behaviour, not the person. For repeated issues I follow the school's behaviour policy and involve parents and pastoral support.
The most important factor is the quality of instruction. Students who are busy with work that is appropriately challenging, and who feel known by the teacher, rarely need to disrupt. Relationship and consistency matter more than any single technique.