Arguably the most vital skill to be acquired when learning to swim. From babies to adults, nothing is more important than the ability to swim and breath.
As with all skills and drills it is strongly recommended that you try it yourself first. Then you can find the best words to describe how it feels to block water from the nose with air and breath out in the water.
This is how I would describe it:
“Breathing is easy, you do it when you are asleep!”
“Breathing in the water is much harder because its 1000 times thicker than air, so you have to force the air through the water. YOU have to tell your tummy when to push the air out.”
Start by proving that water is automatically rejected by the throat:
“Open your mouth wide, hold your breath and go underwater, keep the mouth open wide”.
Real beginners can hold their nose if they are hesitant.
“ Where has the water gone? It went in but then came out. Your mouth automatically ejects the water. BUT the nose does not. There is a direct route to your lungs through the nose, you HAVE to block the nose with air. If there is air coming out, water won’t go in.”
(You won’t always stop it, even good swimmers get water up the nose.)
“Open your mouth and take a big breath. Now push the air out hard and fast, first through the mouth and then through the nose. Water is a 1000 times thicker than air , you have to push hard, EXPLODE the air like a bomb has gone off in your belly.”
“Curl your top lip up and out like you are kissing an orang-utan ( or your Mum, girlfriend, boyfriend etc) to help narrow the nose holes.”
“Hum. Hum a tune. Lips must be closed. Louder.”
“Now hum underwater.” (teacher goes under & checks for bubbles).
Now you can advance to Bobbing and blowing
Add waving, turning, silly faces, shooting a water pistol and always blowing out of the nose.
Homework! Practice in the bath, sink or bowl.
It has to become second nature to blow as you hit water.
Progress to mushroom floats & handstands, emphasis on humming always.
Eventually to somersaults.