Water Lens

Move the water-filled tube up and down across the text. The tube acts as a lens and turns what you see upside down. The same thing happens in a camera and in your eye.

Consider which of the words in the text "Bed och arbeta" can be read if you turn the text upside down. Since the words are written in different colours, it’s tempting to believe that this is significant. If you consider instead the shapes of the letters, however, you realise that it is this that determines whether you see the word as being right side up or upside down.