Here are my thoughts ...................
Firstly, you have been asked to give a 3 minute presentation on the statement, "How to correctly know a nail into a piece of wood" - if you start to think 'out of the box', then they haven't actually asked you to present anything about a nail or wood, so............why not give the talk on the importance of effective communication - bringing into the equation that the given statement was meaningless to many people, therefore it was a good example of non-effective communication. When communication is non-effective, people tend to start making assumptions. My guess is that if you are going for a solicitor's job the interviewers will want to see that you are a person who goes on 'fact' and not assumption ( I am sure that many people here will dispute this
). Perhaps it is a deliberately misleading question aimed at ascertaining which candidates are innovative and effective thinkers.
How I would start the talk would be to ask everyone to stand up - then say 'thank you' and YOU sit down - you will probably find that most if not all of the people will then sit down - then you say - "I did not ask people to sit down again, so you all assumed that if I sat down, you could sit down too............this leads me onto the statment given to me for the presentation.......and so on........."
Only problem is trying to make this into a presentation that will only last 3 minutes
- there could be enough material here to last at least 1.5 hours
Anyway, good luck with the job
PS Personally I don't think you should ignore the given statement and give a talk about something that you are not sure about. It is worded the way it is for a reason.