We had a small cup with some tissue in it (held there by blue tack).
We also had a bowl of water.
When we turn the cup upside down in the bowl of water we all (bar 3 of us) expected the tissue to get wet.
We were amazed to see that the tissue stayed dry!
Are you wondering why?
You see, the cup is filled with air as well as the tissue and blue tack.
When we put the cup into the basin of water, the air doesn't let the water in so the tissue stays dry.
If you tilt the cup as you place it in the water, the water will push some of the air out of the cup, then the water will rush in and wet the tissue.
We like the way that the air can stop the tissue getting wet!