Potential Energy
Energy and Thermal Physics

Simple Siphon

Enrichment Activity for 5-11 11-14

What you need

  • A bendy straw
  • Water
  • Two small flat bowls
  • Food colouring


  1. Fill one bowl with water and a little food colouring
  2. Half fill the second bowl
  3. Submerge the straw in water, making sure you get rid of any air bubbles, and tightly pinch the ends of the straw before you pull it out
  4. Hold the straw with one end in each bowl, and release the ends when they're under the water

Results and Explanation

The water in the bowl with the higher water level is under greater pressure, and so water moves through the straw to the lower level.

These experiments have not been specifically safety tested for home use but we believe them to be safe if the instructions are followed. Adult supervision or direction is recommended as appropriate. All experiments are carried out at your own risk.

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