Walking water

Activity

Discover how water can 'walk uphill' and investigate capillary action to demonstrate how plants take up water.

  • Estimated time: 30 minutes
  • Location: Indoors
  • School term: All year round
  • Level of experience: No experience needed
  • Subject(s): Science, Art&DT

Learning objectives

  • Observe how water can move through paper
  • Investigate the way water is transported in plants
  • Explore mixing primary colours

Essential background information

Preparation

Observe growing plants and trees. Talk about where they get their water from and how it gets to the leaves at the top of a tree.

Equipment 

  • Clear containers 
  • Water
  • Food colouring
  • Kitchen paper

Background information

Plants and trees use capillary action (along with other forces) to pull water up from their roots to the ends of their leaves. Water molecules move through narrow tubes called capillaries (or xylem).

Step by step

 

  1. Use food colouring to make coloured water (blue and yellow).
  2. Pour the same amount of coloured water into 2 clear containers.
  3. Place the 2 containers of coloured water either side of an empty container.
  4. Fold a sheet of kitchen paper into a thin strip. Make 2 of these.
  5. Fold each strip in half, lengthways.These will be the 'ladders' for the coloured water.
  6. Place one end of a strip in the blue colour and the other end in the empty container.
  7. Do the same in the yellow coloured water.
  8. Predict and then observe what happens.

Hints & tips

  • Can all the coloured water 'walk' into the empty cup?
  • Make a 'rainbow' using the 3 primary colours red, yellow and blue - this will take 7 clear containers (put the coloured water in alternate containers).
  • Follow up this activity by placing cut white flowers in a container of coloured water. Leave for some time and observe the effect!

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