Science in Year 6

How amazing is Water?? The year 6 children did an experiment with water & air pressure. The most amazing part?  They filled a plastic bottle, with a small hole in the side, full of water & put the lid on.  They then took the sellotape off the side of the bottle... and voilà, the water stays in the bottle!!  Not a drop escaped!  Is it magic, or is it Science??  Try it at home..