Establish the classroom rules on the very first day of school and keep them posted in several places in the room. Send each student home with a list of classroom rules that is to be signed by parents; this provides parents the chance to make sure their child understands what is to be expected. Reiterate the importance of the rules and to not talk without permission.
Explain the concepts of "teacher time," "quiet time" and "student time." Before each lecture or lesson, announce to the class it is now "teacher time" and you wish for the class to remain silent while you are speaking. "Quiet time" is reserved for reading and studying in class and should also not involve talking. Occasionally there will be "student time" in which the children may talk with their classmates about school assignments or other topics.
Explain and list the consequences for students who talk during class when they have not been called upon or when you are explaining a lesson. Keep consistent with your consequences. If you have a first, second or third offense, make those the same for all students at all times.
Reward students who do not talk or interrupt the class on a regular basis. Keep a chart in the classroom with gold stars or other stickers for when a student is behaving exceptionally well and give prizes and rewards to those students with a certain amount of stars at the end of a week, month or school year.
Remain silent when students are talking until they realize the classroom has gone quiet. It may take a moment, but eventually those students will realize what is happening, stop talking and most likely refrain from doing it again.
Keep moving while explaining a lesson or giving a lecture to the class. Walk back and forth in the front of the room and walk down aisles in the classroom. Children are much less likely to talk in class if they know you are listening.