Sounds like something similar to what I did for GCSE. :)
I took my idea in a sightly different direction, by saying that people can look at the same object and think it is something totally different, just as two people can read the same novel and come up with a completely different idea of what the point of the story was.
I did a little photography (on my digitial camera, nothing fancy) and inverted the colours to show two different views - it is the same object, but it looks completely different. :)