I expect three things from my students whenever someone else is talking; 1- that they look at the person talking, 2- that they are silent, and 3- that their hands are down so they can focus on what the speaker is saying rather than thinking about what they want to say when it's their turn to talk! To remind them I simply point to this sign featuring an eye (look at the speaker), lips crossed out (be silent), and a hand with a down arrow on it (keep your hands down). Print, cut out, laminate, post on wall, and refer to as necessary! Small effort. Big Difference!