In fact, teacher nagging is often an offshoot of stirring the tea. You are the spoon in the teacup. If you want to stir the class up, you must move around. At that danger moment of starting up group or pair discussions, when you’re wondering if they might just sit there self-consciously not saying anything (a tumbleweed moment), you need to get away from the center-front, start moving around. The noise will start. But when you them to quieten down, stop stirring; stand still. I’ve seen so many teachers stirring the class up by walking around, kneeling, disappearing, while periodically nagging them to be quiet. You can’t expect both; you can’t stir the tea and expect it to remain stationary.