Sunday, May 6, 2012

Finding out why leaves change colour in Autumn

This term we are learning about changes.  This week we have been looking at the changes in seasons and we wanted to know why the leaves change colour in Autumn so we did an experiment.
For this experiment we needed leaves from an evergreen, and green and autumn coloured leaves from deciduous trees, plus some rubbing alcohol and a coffee filter sheet.










 
We cut up the leaves really small with a plastic knife and put them into jars that we covered with rubbing alcohol and labelled.  Then we covered the jars with plastic film and placed them in a tray full of boiling water.  After half an hour we checked to see if the colour from the leaves was showing in the liquid.

Autumn deciduous leaves
Autumn deciduous leaves
Deciduous green leaves

Deciduous green leaves
Evergreen green leaves













We uncovered the jars and placed strips of the filter paper into the liquid.  We checked the jars after half an hour and then again another half hour later. 

Look at our results -
Deciduous Autumn leaves
Deciduous Autumn leaves
Green deciduous leaves


Green deciduous leaves
Green evergreen leaves




















What we discovered:



Plants make their own food. They take water from the ground through their roots. They take a gas called carbon dioxide from the air. They turn water and carbon dioxide into food and oxygen. Oxygen is a gas in the air that we need to breathe.
Plants make their food using sunlight and something called chlorophyll. Chlorophyll gives leaves their green colour.

 
Winter days are short and dry. Deciduous plants stop making food in the autumn. The chlorophyll goes away. Then we can see orange and yellow colours. These colours were in the leaves all summer, but the green covered them up.
Some leaves turn red. This colour is made in the autumn, from food trapped in the leaves. Brown colours are also made in the autumn. They come from wastes left in the leaves.


4 comments:

  1. What a nice experiment.I think that doing a experiment for the season autumn is a great idea how did you think of it?
    From Afifah

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  2. We found this idea out from an internet search when we were learning about autumn and why the leaves change.

    ReplyDelete
  3. Hamish was very excited about this experiment and told me the steps you had to take. It was great to be able to look at the blog and check if he was right.....( he was).

    From Sally

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  4. We think that the experiment you guys have done was very interesting.Do you want to do more experiments for autumn?

    From Afifah and Makki

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