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.