Materials Required:
An empty soda or water bottle with the label removed
A small amount of play dough, plasticine, or clay
A straw
Water
Steps Involved:
Cut a small length of straw.
Plug one end of the straw with play dough.
On the opposite end of the straw, make a ring of play dough around the outside of the straw, so the straw is weighted but remains open at that end.
Fill the bottle three-quarters full with water.
Drop the straw into the mouth of the bottle and screw on the lid tightly.
Squeeze the bottle as hard as you can and observe the straw sinking.
Tip: If the straw doesn’t sink, try squeezing the bottle at the top where there is no water or lift the bottle off the table while squeezing.
Discuss the results:
When the bottle is squeezed, the air inside is compressed, increasing the pressure, which pushes water into the straw and makes it sink.
When the pressure is released, the air pressure decreases, allowing the air to fill the straw again, making it float back to the top.