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The labour of leaves

Every plant in your garden is an energy factory, and their leaves are the labourers. Head outside and take a sneak peek at them working in this simple experiment.

What you need

  • Two glasses
  • One freshly cut large leaf
  • A sunny spot for your glasses to stand on, such as a window ledge


  • Fill both glasses with water and place your leaf in one of them. Make sure it’s completely submerged. 
  • Leave the glasses in a sunny spot for at least half an hour.
  • Check which glass of water has more bubbles in it 

The science

We can use the sun’s energy to power our homes, but we can’t use it to power our bodies. Plants can, however, which makes them an extremely important part of food chains. They use sunlight, carbon dioxide and water to produce a kind of sugar and to release oxygen. Other life-forms, like us, can use the energy in that sugar and breathe the oxygen. 

This transformative process is called photosynthesis, and it takes place in a plant’s leaves. That’s why the glass with a leaf contained more bubbles than the one without – the leaf was photosynthesising and releasing oxygen into the water. 

Otago Museum has lots of rainforest plants in its indoor Tropical Forest! There is a banana tree, a coffee bush, and one of the largest fiddle-leaf figs in New Zealand. When our butterflies arrive in their cocoons from tropical countries in Asia and South America, they feel right at home when they hatch out to flutter around the greenery.


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