Chances are, you already have your own method of teaching breath support. Chances are, it matches up perfectly with breath support practices in clarinet playing. So, this will be quite abbreviated. Also, too much can often be made of proper breathing---to the point where all sorts of unnatural physical things start to happen.
If you stress: sit tall, full breath, fast air...in your own words, of course, that's enough. Be sure that the student is not slumping forward, that he takes a breath similar to a big sigh, and that he understands that the air is to be expelled as though trying to blow out candles. When you stop to think about it, if you are sure the student is sitting correctly, getting him to take a deep breath is simple: he's been doing it all his life. The only unfamiliar part is air intensity. Even that is easy with such statements as:
"Blow out making the loudest, longest, hissing sound you can."
"Imagine a piece of paper flat against the wall; blow a fast enough air to hold it there as long as you can." (The real physical act of placing a piece of paper against the wall will actually work.)
Forming the Embouchure
Present each of the students with his own reed/ligature/mouthpiece/barrel combination. Also have your own prepared and ready to assist in demonstrating. Instruct the student to firmly grasp the barrel with his left hand (a preliminary move which eventually establishes the left-above-right hand position). Demonstrate and mention that the reed faces toward the student. Also give caution about rubbing the reed against clothing, chipping the reed, etc.
Now, using your own facial expression and voice, instruct each student to "make an exaggerated, facial 'A' sound." The muscles which control the chin and lower lip must visibly move: the lower lip plus the muscles and tissue covering the chin becoming very flat. To be certain that a facial 'A' is formed, the visual image of "showing a deaf person the letter 'A' with your facial muscles" is usually very clear. If not, this is: "Imagine you are putting Chapstick on your lower lip. Run your finger over your lip as though it were the tube of Chapstick." (If you look in a mirror, you will notice that the famous "flat chin" portion of the clarinet embouchure has been formed.) Now instruct the students:
"Maintaining the feeling of the facial 'A', add a facial 'Q' on top of it." (It is the "oo" sound we are interested in.) This instantly brings into position the muscles which surround the lips and completes the formation of a perfect clarinet embouchure.
THE FIRST TONE
The next step is to couple the embouchure formation with the reed/ligature/mouthpiece/barrel combination. It is important to mention that the reed rests on the lower lip, while the upper teeth contact the mouthpiece. Instruct the student to take about half-an-inch of reed into the mouth. (Watch the angle of the mouthpiece/barrel combination to the body; keep it down. Also note head position; keep it up...level.) Demonstrating for the student, explain:
Take a deep breath, re-form the embouchure ("A-Q"), and "blow out candles." Your demonstration will produce top line, concert F#.
Testing each student individually you will encounter one of six predictable results:
#1--CORRECT RESULT More often than not, a reasonable tone results. Imitation of your tone and pitch will be automatically attempted. When it happens , the sound of mouthpiece and barrel produces concert F# (clarinet G#) and should sound like this:
#2--NO TONE, RUSHING AIR In this instance, there is only one cause: No pressure of any kind against the reed. It always sounds like this:
REMEDY: Increase lower lip pressure against reed.
#3--SQUAWK-LIKE TONE or FLAT PITCH These sounds:
are created in three possible ways:
a. Insufficient pressure against the reed.
b. Too much reed in the mouth.
c. Insufficient intensity in the air flow.
REMEDY: Check visually for too much reed; if confirmed, the sound will usually be squawk-like (3a) rather than low-pitched. If, on the other hand, the tone is more like 3b (low pitch), ask for increased lip pressure and/or increased air intensity. To check this, ask the student to demonstrate the air flow by playing on the mouthpiece/barrel unit and then while still blowing, remove it from his mouth. The air intensity question will be immediately answered. Sometimes an increase in air intensity alone will solve the problem; other times a request for "faster air and a bit more firmness against the reed" may be necessary. [continued]