It goes without saying that breathing is at the heart of wind playing. How such a very natural component of our daily existence can become so complicated in pedagogy! I always remind young students to watch their pets breathing when they are asleep, (our own dogs sleep a lot so it's easy to catch them in the act of breathing naturally) and to describe what part of the body they notice moving with the breath...this helps students locate the correct area for diaphragmatic breathing. Have students lay down on the floor on their backs, and place a book just at the bottom of the rib cage to observe this correct and deep way of breathing. It helps to remember that breathing will raise the chest area a little bit (think sternum rising just a touch) and the ribcage will expand outward. The shoulders do NOT move up and the breath is a horizontal kind of physical endeavor, never vertical! For advanced students who breathe correctly but do not get enough breath support for tonal fullness, ask them to play the same passage flutter tongued or ask them to sing and play at the same time. Both of these extended techniques require a LOT more breath support than traditional playing, and feeling the difference will bump up awareness of how much air the flute can take.