One of the biggest mistakes people attempting there adi part 3 test make is that the vast majority of people simply do not prepare for pst 1 the controls lesson. It seems the common view is "I know how a seat works and I know how a seatbelt works so what do I need to revise?"
And that is the quickest route to failure you can find!!!
When you become a driving instructor, your part 3 test is a teaching ability test, therefore the more you can tell aperson something, the more they understand WHY they need to do it.
For instance when it comes to the controls lesson, you really need to fill in at least 4 statements
1- What it is
2- What it does
3- How it works
4- My commands will be
Take as an example the accelerator. Going through our 4 statements.
1- The accelerator but for driving instruction purposes we call it the gas pedal, just because it's easier for me to say "off the gas" rather than "Can you please take your foot off the accelerator", because by the time I've said "Can you please take your foot off the accelerator and you've said what?" We've already gone past whatever it was I wanted you to slow down for.
2- It controls the flow of fuel to the engine,
3- it operates much like a tap, the more you turn a tap the faster the water comes out, well the harder you press the pedal the faster the fuel flows to the engine and the quicker the car goes. Likewise when you release the pedal, it shuts off the flow of fuel to the engine and therefore helps the car to slow down. So we only need to press it gently
4- On the gas which means press the pedal gently down, Off the gas which means raise your foot off the pedal, Fraction on the gas which means just press the pedal slightly down and fraction off the gas which means just raise your foot slightly off the pedal but not all the way.
At the same time as getting the pupil involved in this (you can always liken it to pressing the pedals on a bicycle) you need to be watching for any faults, which in this case is likely to be the examiner continually pressing on the gas pedal. Which of course in an older car may result in flooding the engine.