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.  :)

Irreversible Change

Irreversible change.  Sounds like lots of fun for a 4 year old, right?  Heck ya! Irreversible change, introduced to most by Sid the Science Kid simply means, "no take backs." For this experiment, kids learn about the physical properties of objects.

Ingredients:

•  Apples
•  Water 
•  Bowl

We are going to create applesauce:
Hand the kids a whole apple and encourage them to try to mash the apple. Depending on the little scientist's tenacity, this should be complete failure. My scientists threw the apples and banged them against the table to no avail. It wasn't until one found a bruise and used his fingernail that he had moderate success, but still no applesauce.

Next, I gave the kids a potato masher and bowl filled with sliced apples. They set to work trying to mash those apples into applesauce. Some of the apples broke down, but still no applesauce.

What happens if you add heat? Add a small amount of water to a microwavable bowl and seal, lifting a corner to allow steam to vent.  Zap on high heat for 10 minutes. For those interested in making super yummy applesauce, check out this delectable treat: 10 Minute Applesauce. (Hint: to help keep your scientist's attention, you may want to start heating apples early.  Trust me, if you try the recipe above, you won't mind the extra applesauce.)

Allow the mushier apples to cool a bit (you may want to check the texture to ensure the experiment won't backfire on you).  I transferred the mixture to a larger bowl, because by this point, the mashing tends to get frantic.  We used the chant, "Up, down, turn around" to help the kids from going too crazy and perhaps get better success.

For the adventurous types, I suggest whipping out the immersion blender at this point (for personal or mature kid use). Not only will the finished product resemble store bought applesauce, but you can also pose another question: What do you think will happen next?

For the Younger Scientists:
Rehash what just happened. Then ask: Do you think we could take this super yummy applesauce and change it back into a crunchy apple? You may want to ask about other things like mashed potatoes, cooked veggies, etc.

For Older groups:
This is a simple way to introduce the simple states of matter: solid, liquid, and gas. Point out that the whole and sliced apples represented solids; i.e. placing them in a container did not effect their shape.  While taking the top of old the heated apples note the steam (gas) escaping and dissipating as it tried to fill the room. Last we have the runny part of the apple sauce which is a liquid and as such will take the shape of its container.