"I WANT IT QUIET IN HERE!"
Our job is to place knowledge and skills inside the noggins of our learners. How frustrating that mission becomes when we are unable to do our job proficiently because our students are engaged in off-task conversations. At other times, it is the sound of learning that we are hearing, but it's many decibels too loud. How can we give ourselves a classroom noise "mute" button or volume control knob? Here are a few ideas, followed by an excellent resource for reducing noise levels:
Entering The Classroom
1. As you bring your students to the door of your classroom, stop just before entry. You or an assigned student moves down the line, using touch and finger to the lips to convey to talkers that it is time to be quiet. You have previously talked about and practiced the entry routine... walk with lips closed directly to one's desk, and place materials on the desk that are needed for the next class. (or similar procedure, depending on the nature of the upcoming class session)
2. If students enter individually, be at the door to greet them. Allow well-behaved, quiet voiced students to enter. Send loud and boisterous students back to a point about 10 yards/meters away. Have them approach you showing correct behavior and voice volume.
3. Each and every time that students enter your room, have a "Do Now" activity written on the board, projected onto the screen, or placed on each student's desk. You have practiced and promoted this "Do Now" activity. Upon entry to the room, students immediately engage in the task presented. That task is a review of what was taught previously (to bring your charges back up to speed, cognitively speaking), or something that will prepare them for the upcoming material that will be taught. (My favorite of the ones that I've seen: "Work with your partner to list words that rhyme with orange, purple and silver."... There are no English language words that rhyme with these! It'll keep them busy for awhile. Hey... how about "door hinge" as a sound-alike for "orange"?)
In The Classroom
1. Talk about noise levels during the first day(s) of the year. Have students practice different volume levels as they read something on the wall or repeat what you say. Compliment for effort and progress.
2. Help your students better understand the level of "quiet" that you desire for a particular activity. Operationalize what you mean by identifying the distance that their voices should travel... "With your partner, use your hand length voices.", "Use your arm's length voices please.", "Use your table voices for this activity.", "You may use your outside voice until we line up in 20 minutes to re-enter the building.", "As soon as your foot touches the school building floor, your lips are closed until you are back in your seat in the classroom."
3. Notice times when the students are displaying the correct attentive behavior and/or voice levels. Use specific praise that identifies the action that you appreciate. ("The red group is doing a wonderful job of using their table voices.")
4. Develop a signal system. When you want quiet and student attention directed toward you, show the signal (hand raise, finger to closed lips, etc.). Students acknowledge you by showing the same signal. Of course, this system needs to be practiced, and students need to be positively recognized for having followed your lead.
5. Develop a classroom chant that the students repeat when they hear you say it. They then close their lips and attend to you. For example: "One, two, three. Eyes on me." at which time the students reply, "One, two. Eyes on you."
6. Teach the students to repeat your clapping sequence. When you need their undivided attention, clap a rhythm. Students repeat that cadence. Then clap again using a different "tune". At that point students attend to you.
7. Count down from 5 to 1. At one, students should be silent and attentive to you. (Again, practice, practice, practice... and praise, praise, praise.)
8. Rather than getting louder to try to talk over noise, reduce the volume of your voice so that the students have to lower their volume to hear you.
9. Repeatedly set a twist-the-dial timer. Sometimes it will take 10 minutes before a bell sounds. Other times it will take 2 minutes. (Hide the dial from sight of the students) Evaluate whether the class was using the correct voice level at the time of the sounding bell. Give one point (toward the 25 or 50 that are needed for the group to earn a priviledge/prize/reward) if the class was using the correct volume level. You will find that students remind their peers to "quiet down" in an attempt to earn the points more quickly. For more information, see the page on this site for "Promoting positive peer pressure".
DO NOT penalize the entire class for the loud behavior of one or two students. Recognize the efforts of the majority, and set up separate systems for the persistent offenders (see the page on this site for "Self-recording).
10. Visit the "Teacher.TV" web site and watch the video at: http://www.teachers.tv/videos/sharing-expectations
11. Teach correct voice levels with the teaching tool found at: http://elearning.autism.net/visuals/main.php?g2_itemId=135 (while designed for teaching students with autism, it would serve as a useful tool for any teacher)
12. Give warnings about being "too loud" in a non-verbal manner (so that we don't yell louder than the volume of our students). Say a student's name quickly (or otherwise gain his/her attention), and hold up one finger (symbolizing "first warning"). Hold up two fingers for the second warning. Wave the student to you for the third consequence (whatever you have decided upon and discussed previously with the students).
13. When the classroom is noisy, look for students who are using the correct voice levels. Recognize them positively.
14. Model the voice level that you wish them to show.
Here's the resource that I was speaking of. Click on the image for more information. 
Author: Tom McIntyre www.BehaviorAdvisor.com