Decidu-whaaaa?!?

With a few goofy exceptions (you know who you are), fall is a beloved time of the year.  The changes are apparent to all. Crisp air, new aromas and fresh colors abound.  Many kids are quick to notice these changes and ask why?  Here is a simple experiment to help explain why leaves fall from trees.

Explanation for the Head Scientist:  




Leaves are the chefs for the plant. It is their job to convert water, sunlight, and carbon dioxide into glucose.  This process is called photosynthesis.  In the fall, the days become shorter and water is scarcer. As such, the kitchen starts to close down. As the temperature drops, the membrane that passes the water and glucose between the plant and leaf closes, and the leaf falls off. (The change in temperature and the tree type cause the variation of leaf colors).

 Experiment: Coloring with Chlorophyll

Ingredients:

• Green leaves
• Various colored leaves
• White paper
• Coin

Pre-Experiment Explanations:

• Ask your scientists what three things plants need to survive: 
• Water 
• Sunlight
• Nutrients.  
• Explain that the days are getting shorter in fall and it rains less. 
• Super savvy scientists may want to use a globe and flashlight and show how the Earth tilts away from the Sun during Fall & Winter.
• Explain what a leaf is to a plant.

Hypothesis:

• Why do you think leaves change color in fall? 
• Ask the scientists about any other changes they may have noticed (i.e. weather, clothing, day length).

Experiment & Observation:

• Place a green leaf on the white piece of paper. 
• Rub the coin on the leaf. You should see green on the paper (chlorophyll).  
• Next place a colored leaf on the paper and rub with a coin. 
• What happened? Results will vary depending on color chosen. 
• Try to save a brown leaf for last. Rub the coin over the brown leaf. 
• Nothing shows up on the paper. 

(You may also want to tear leaves of various colors to notice the difference in textures.)

Conclusion:

• Leaves change color because they are getting less of the necessary things they need to make food.  
• Ask if all plants lose their leaves. 
• The plants that lose their leaves are deciduous and those that keep their green leaves are called evergreens.  
• Now: Try saying deciduous 10 times real fast.  :)