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

Learning objectives

  • Observe how water moves through paper via capillary action
  • Investigate the way water is transported in plants

Essential background information

Preparation

Observe growing plants and trees and identify the different parts of the plant e.g. roots, stems or leaves. Talk about  how plants access water through its roots and how the plants transport water up to its leaves.

Equipment 

  • Three clear containers - glass jars or cups
  • Water
  • Two different colours of food colouring (blue and yellow work well)
  • 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. Add 3cm of water to two of the clear containers.
  2. Add food colouring into the water, making each one a different colour. Use blue and yellow food colouring to make coloured water.
  3. Place the two containers of coloured water either side of an empty container.
  4. Fold a sheet of kitchen paper into a thin strip. Repeat this so that you have two folded pieces of kitchen paper.
  5. Fold each strip in half lengthways.These will be the 'ladders' for the coloured water.
  6. Ask your pupils to predict what will happen to the coloured water. How the water travels up the kitchen paper, what will happen to the water levels in each container and what will happen when the colours mix together in the middle container.
  7. Pace one end of a strip in the blue colour and the other end in the empty container.
  8. Do the same in the yellow-coloured water.
  9. Pupils will then observe what happens and compare the results to their predictions.

Hints & tips

  • Can all the coloured water 'walk' into the empty cup?
  • Link into the Art & DT curriculum by making a 'rainbow' using the three primary colours red, yellow and blue - this will take seven 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.