Try this low prep or rather, almost no prep science activity that will make you look like a wizard!
What you need
Large bowl of water (big enough to submerge the glass)
Small clear drinking glass
Step by Step
1) Fill the large bowl with water, enough to submerge the glass.
2) Add food colouring (to see the effect better).
3) Turn the glass upside down, keep it fully submerged.
4) Get your child to make a prediction - What do you think will happen when the upside-down glass is slowly pulled out to the surface of the water? Will the coloured water stay in the glass or spill out?
5) Lift the glass up. Make sure you the top of the glass remains at the surface of the water in the bowl.
6) Hover around the surface. What do you see? The water magically remains in the glass even though it is not fully submerged.
7) Now, lift the glass fully above the bowl, breaking the surface. What do you see?
The water stays inside the glass even though it is being lifted up because air pressure is pushing down on the water's surface. This forces the water to remain in the glass. When you lift the glass above the surface of the water, the air pressure that keeps the water in midair is released. Gravity then causes the water to gush out.
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