Using questions to discover a pupil's skill level is one of the most important parts of the part 3 test. Potentially, with a skilful question and answer tecnique, it's possible to prevent the examiner from committing certain faults before you even move off.
The key to this is to know your subjects - that way you can spot gaps in your 'pupil's' knowledge when they reply.
The Phase 2 Sample Questions will give you an understanding of the type of questions you should be asking in order to get your pupil to give answers you'd expect to hear.
The questions & answers will also help you learn the PST subjects as you use them - the question pages include visuals to help trainees remember the answers.
It's amazing how much more confident PDI trainee driving instructors become when they finally begin to learn the correct technique of Q&A. They can literally get pupils to reveal their driving weaknesses before a lesson starts!