Backyard Water Experiment
Try this experiment outdoors, or over the kitchen sink.
--Fill a glass to the brim, with no air or bubbles left on top
--Next, slide a flat, dry piece of sturdy cardboard over it.
--Hold the cardboard in place, and turn the glass upside down.
--Let go of the cardboard and see what happens!
If you did the experiment correctly, the cardboard should stay in place. As you can see in our experiment #3, it won't work with soggy cardboard!
This happens because the air pressure that's pushing up on the cardboard is greater than weight of the water that's pushing down on the cardboard.
We found this experiment in Scienceworks: An Ontario Science Centre Book of Experiments
