STORY LINKS: Walking on Water

The Leaky Bottle Trick

Pupils explore surface tension of water and discover the remarkable relationship between surface tension and air pressure.

Age Group: 9-12 years

Duration: 20 minutes

Biomimicry Connection:

This activity shows the concept of surface tension in water, which is used by water striders to stay afloat and move on water surfaces. Understanding this principle not only shows the mechanism water striders use, it also provides a source of inspiration to solve human problems and create innovative designs.

Activity Details:

Tools and Materials

  • Plastic bottle with a cap
  • Push pins or thumbtacks (at least 5)

Description

This activity will help pupils to visualize surface tension.

  1. Fill the bottle with water and close with the cap.
  2. Take 5 push pins per bottle and insert them into the bottom of the bottle so they make holes into the bottle.
  3. Remove the push pins. Why doesn’t the water drip out of the holes?
  4. Now open the cap. Why does it come out now? Explain that this is because of the air pressure that enters from the top.