Forget interactive whiteboards and clever progress-tracking spreadsheets. The most important tool in any classroom is the teacher's voice. What other tool can explain, encourage, challenge and reprimand?
But like any part of our bodies, our voices need to be looked after.
A 2008 study into vocal problems in the teaching profession, undertaken by the Royal National Institute for Deaf People, found that teachers in 59 per cent of schools surveyed had suffered vocal strain, with almost 73,000 teaching days per year lost through voice-related complaints.
Given these figures, it is important that all teachers understand what they need to do to protect their most powerful teaching tool.
The following "three Ps" of effective use can make all the difference:
As with most things in life, preparation is key. But how many of us do anything to prepare our voices?
Just like Usain Bolt wouldn't dream of running 100m without warming up, professional voice practitioners, such as actors and singers, spend prolonged periods in preparation. Warming up the various speech components is vital for the effective and safe use of the voice.
First, make sure that you are relaxed. Muscular tension can lead to inefficient voice production and potential strain and injury. Start with some shoulder shrugs and neck rolls to loosen up the neck and shoulders before moving on to the face and neck.
Try tightening and releasing all of your facial muscles. Exaggerated yawning and smiling will also help to loosen up the face and jaw.
Voice is produced by the interaction of your diaphragm, larynx, nose and mouth. While the diaphragm ensures sufficient power to produce the voice and the larynx controls the vocal cords, the nose and mouth enable the sound to resonate.
Posture affects all aspects of diaphragmatic breathing, which is why you would usually stand to sing and should do so when teaching, where possible. Shallow breathing leads to strained voice production, making effective projection impossible and increasing the risk of injury.
To encourage effective production, start by standing with your hands on your stomach. Breathe in slowly to a silent count of five, focusing on feeling your stomach rising. Then release the breath to the same count, focusing on feeling your stomach fall.
Next, make long vowel sounds ("aaaa", "oooo", etc) and then pick a few consonants and focus on the production of their sounds.
The physical environment can affect acoustics dramatically . It is important that you adapt the way in which you use your voice as necessary. Large spaces, for example, can produce echoes.
Overcome this problem by slowing down and clearly enunciating your speech, rather than increasing its volume. Using a mixture of verbal and non-verbal signals to gain attention can also be helpful.
Most importantly, be aware of early signs of problems and seek medical advice if the symptoms don't clear up within a fortnight.
16 April 2016 is World Voice Day.
Jason Dickinson is a former English and drama teacher. He works as a freelance writer, NQT external mentor and NUT assistant division secretary. He tweets at @writeonjason