You should be able to demonstrate that you can do all the stuff that you will need to do on your own once you get your PPL.
An examiner friend of mine makes this a little more fun. He asks the candidate to imagine that they have flown to France for lunch. He tells them how much fuel they have, how much he weighs, and also the weight of a bottle of wine. He asks them to calculate the maximum number of bottles of French wine they can bring back and then the take off distance required :-)