Most disruptions are minor: side talk, a phone out, a late arrival. The goal is to stop the disruption with the least intervention that works, so you do not turn a small thing into a scene. A pause, a look, moving closer, or quietly naming the expectation usually does it.

Address the behavior, not the person, and keep your tone even. Public call-outs and sarcasm tend to escalate and cost you goodwill with the whole class. If a minor behavior persists, a brief private word after class is more effective than a confrontation in front of everyone. Save your energy and authority for the few situations that truly need them.