At the beginning of your practical test the examiner asks two vehicle safety questions. The first is a 'tell me' question asked before you move off: you explain how to perform a safety check. The second is a 'show me' question asked while you are driving: you demonstrate a safety task without losing control.
'Tell me' questions cover topics such as how to check the brakes before setting off, how to check tyre pressures and tread depth, how to test the headlights and tail lights, how to check the engine oil level, and how to top up the windscreen washer fluid. You answer verbally; you do not need to demonstrate physically.
'Show me' questions require you to operate controls while the car is moving. Examples include washing and wiping the windscreen, demisting the front and rear windows, opening and closing a side window, switching on dipped headlights, and activating the rear demister. You must carry out the action while maintaining full control of the vehicle.
A wrong answer to the 'tell me' question counts as one minor fault. An incorrect 'show me' demonstration also counts as one minor fault. However, if you lose control of the car while trying to perform a 'show me' task, that could be marked as a serious fault.