by Diane Burdick, Ed.S.
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When you hear the word “marshmallow,” what comes to mind? Maybe you think of s’mores, or maybe of the party game where you cram your mouth with marshmallows while saying “chubby bunny.” But, if you’re science-minded, you may have different ideas altogether. Here’s just such an idea: a fun experiment with marshmallows that illustrates Charles’s Law.
This “law of volumes” explains that the amount of space something takes up increases as the temperature increases. And, as it turns out, a heated marshmallow is just the ticket for illustrating this principle to children.
Things you’ll need:
• 4 large or jumbo marshmallows
• Microwave-safe plate
• Paper towels
• Microwave
Steps:
1. Place a paper towel on a microwave-safe plate, and place one marshmallow on the paper towel.
2. Heat the marshmallow on high power for 10 seconds. Notice the shape and size of the marshmallow, and record any changes from its original shape. Students can use illustrations, adjectives and sentences in their notes. Allow the marshmallow to cool and note its shape.
3. Heat a second marshmallow on a paper towel in the microwave; heat on high for 30 seconds. Notice the shape and size of the marshmallow, and record any changes from its original shape.
4. Heat the third marshmallow on a paper towel in the microwave; heat on high for 50 seconds. Notice the shape and size of the marshmallow, and record any changes from its original shape.
Thinking Questions:
• Which marshmallow expanded the most?
• Which marshmallow shrunk fastest?
• Did the marshmallows ever return to their original shape or size?
What’s Happening:
Visualize the outside parts of the marshmallow as a flexible container of air. When the air inside this container gets hot, the marshmallow will expand, and therefore, the container will also grow and take up more space. As the temperature drops, the volume of the gas decreases, and the size of the marshmallow decreases as well.
Inspiration Source:
Kitchen Science Experiments: How Does Your Mold Garden Grow? by Sudipta Bardhan-Qualen
A Learning Experience 