Answer:
Give clear instructions to the students so they know what they need to do. State the consequences of misbehaving as well to decrease the chance of a student misbehaving. Make sure to follow through with your punishment if a student misbehaves so that they know that you were serious. Also, compliment the students when they are all doing their work and not messing around. This will reinforce that they have made the right decision and encourage them to do it in the future.