The test is conducted by a qualified senior examinor (SE ADI) and lasts for about 1 hour. You will have to demonstrate, through your practical teaching and coaching skills, that you are able to pass on your knowledge to pupils with 2 different levels of ability.
There are two parts to the test. In the first part (phase 1), the examiner will play the role of a beginner or learner with limited driving skills. For the second phase, the examiner will play the role of either a learner who is about at driving test standard or a qualified driver undertaking driver delelopment training.
Make no mistake, this is the hard part of the qualifying process. To have any chance of passing this part you'll need a thorough knowledge of the theory. Currently and historically figures from the DVSA show a pass rate of about 30% or less, for the part 3 test.
There are 10 PST's covering the subjects above, from beginner, partly trained, trained to full licence holder (FLH).