Say to your students, "If you can hear me, clap once; if you can hear me, clap twice." Continue until the class gets quiet and ready to settle into the lesson.
Come up with a distinct clapping pattern. Teach it to your students on the first day of school. When you want them to get quiet, begin clapping the pattern. They should become quiet and clap the pattern back to you. Repeat as necessary.
Teach your students to "give me five" at the beginning of the school year. When you hold up one of your hands like a stop sign, your five fingers signal them to: stop talking, sit back in the chair, put your feet on the floor, hands on the desk and your eyes on the teacher.
Allow your students to talk to each other while they are working on a project or doing class work. Teach your students that this is their time and it is appropriate to talk during this time. Let them know what they are allowed to do during this time; sharpen their pencils, use the bathroom or get a drink of water.
Teach your students what you expect them to do while you are giving instructions or presenting a lesson. Let them know that it is appropriate to take notes during this time but the only other thing they should be doing is looking at you. No talking to their classmates, getting out of their seats or looking through their backpacks or desks. This is your time and you can teach your students to respect that.
If students continue talking, stop talking. Do not under any circumstances continue your lesson until they are all silent. Let them know that you will sit there quietly until they all stop talking. Issue appropriate consequences as needed. Over time, as long as you are consistent, most students will not feel the need to test you further.
Let your students know when you are about to ask a question. Tell them you want them to think about it for at least a minute and then quietly raise their hands when they have an answer. This helps to prevent calling out and allows time for students who may be slower to answer to have an opportunity to be involved.