# Sizing Up Marshmallows

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#### Updated on Jun 14, 2013

Grade Level: 3rd to 5th; Type: Physical Science

### Objective:

This project determines if air pressure will cause a marshmallow to expand when heated in a microwave.

### Research Question:

• What happens when you heat a marshmallow?

Marshmallows are mostly made up of sugar and water surrounded by air pockets. These air pockets inside the marshmallow expand and push against the sides of the marshmallow. Since the marshmallow is flexible, will it expand?

### Materials:

• Four marshmallows
• Paper towels
• Microwave
• Pen and/or pencil
• Lab notebook

Note: The marshmallows can get very hot. Adult supervision is required for this project.

### Procedure

1. Place one marshmallow on a paper towel and place it in the microwave. Heat it on high for ten seconds. Remove the marshmallow from the microwave and compare it to the appearance of the unheated marshmallows. Record your observations.
2. Allow the marshmallow to cool at room temperature and then record any changes to its appearance and texture.
3. Place a second marshmallow on a paper towel and place it into the microwave. Heat this one on high for thirty seconds. Remove the marshmallow from the microwave. Again, compare it's appearance to the unheated marshmallows. Record your observations.
4. Allow the second marshmallow to cool to room temperature and record any changes to texture and appearance.
5. Place the third marshmallow on a paper towel and put it in the microwave. Heat it on high for sixty seconds. Remove the marshmallow from the microwave and compare its appearance to the last unheated marshmallow. Record your observations.
6. Allow the third marshmallow to cool to room temperature. Record any changes to appearance and texture.
7. Analyze your results. Did the heated marshmallows expand in size? Which marshmallow expanded the most? Did heating the marshmallows longer allow them to expand more or melt? What happened to the marshmallows as they cooled? Did they return to their original size and shape?

Terms/Concepts: pressure; texture; appearance; room temperature

References: