Some students just love to talk. They seem to have opinions about everything and are not shy about expressing them. They might stop talking in response to a teacher's request, but five minutes later they're at it again. Their talking can become contagious. If students see that a classmate is allowed to get away with it, they might start talking as well. The resulting chatter can significantly disrupt your classroom activities and impede your ability to teach a lesson.
In your effort to gain quiet, you need to pay attention to the nature of your instruction, as well as to the structure in your classroom. That structure needs to include a clear rule regarding talking, and a willingness to enforce that rule consistently without antagonizing students. Also, bear in mind that you do not want to discourage all talking by your students. Indeed, students talking among themselves can be a real source of learning, as exemplified by cooperative learning groups.
WHAT YOU CAN DO
Communicate your rules regarding talking. In conveying those rules to students, make it crystal clear when students are allowed to talk and when they are not. You might, for example, tell them it's okay to talk when they raise their hand and are called on, when they need information to finish an assignment, or when they have completed their seatwork (as long as they talk in whispers). You might also tell them that they are not allowed to talk when you are teaching, when a classmate is asking or answering a question, or when they are taking a test. Teach them the signal you will use to cue them to stop talking.
Cue the student to stop talking with a pre-arranged signal. Talk with him privately and agree on a signal you will give when you need him to stop talking. Get his agreement to the plan and ask for his suggestions about a signal. Some possibilities: pausing while you are speaking, raising your eyebrows, tugging on your ear, or winking. You might need to say his name to get his attention before signaling him, but do not stop class to reprimand him. The idea is to give him a reminder without interrupting the flow of your lesson.
Stand by your students. If a student is talking while you're teaching, move in his direction while continuing to present your lesson. Stand there for a minute or two, perhaps making eye contact with him. Your presence likely will be sufficient to quiet him down. It is a good practice generally to move around the room in an unpredictable manner and vary where you stand when you present your lessons.
Do not bail out a student who has been talking. A student who is gabbing with his neighbor might miss out on directions or part of the lesson. If he asks you to repeat them, tell him to figure out another way of getting the information. Let him know that he would have heard the directions if he had not been talking. You might avoid the problem by saying to your students before giving directions "I'm only saying this once."
Use a noise meter. Try this simple strategy for quieting a noisy class. In the morning draw a noise gauge on the board and divide it into five or ten parts. Each time the noise reaches an unacceptable level in your class, fill in the gauge up to the next point. If the noise is really loud, you might go up an additional increment. If the gauge becomes filled to the top, consider imposing a consequence that you have previously discussed with the class. You also can use this strategy in a positive manner by rewarding the class at the end of the day if the gauge has not risen above a certain point. Start with an empty gauge every day. The advantage of this technique is that it helps quiet the class without you speaking to students.
Keep track of noisiness using a stopwatch. Start the stopwatch as soon as the class becomes noisy and stop it when the class quiets down. Make sure students see you doing it. Let them know that the amount of time they have been talking will be taken away from their recess or made up after school. You might also reward them if they keep the amount of time they're noisy under a pre-set standard.