Giant marshmallows!

Giant marshmallows!

Make a monster marshmallow

Do you want to make a monster marshmallow?

What you need:

  • Marshmallow
  • Paper plate
  • Microwave
  • Toothpick
  • Food colouring

What to do:

Ask an adult for help using the microwave.

  1. Dip a toothpick in food colouring and paint a face on your marshmallow.
  2. Put the marshmallow on a paper plate. Put the paper plate in the microwave.
  3. Microwave the marshmallow for around 45 seconds on high power.
  4. Watch your marshmallow through the microwave window. What's happening to it? Your monster face should be growing!
  5. When the time is up, take the plate out of the microwave. Be careful, as the marshmallow will be hot.
  6. Wait for around ten seconds and then eat the marshmallow. What do you notice about it?

You can repeat the experiment as many times as you like! If you leave the marshmallow for a couple of minutes it will shrink back down to its original size and then get hard and crunchy. You can still eat it.

If the marshmallow goes brown or black, the sugar has burnt. Try again, but this time microwave the marshmallow for a shorter time or on a lower power setting.

What's happening?

Marshmallows are made of sugar and water with lots and lots of air bubbles. If you heat the marshmallows in the microwave, the microwave heats up the water. The hot water heats up the sugar, which makes it softer. The hot water also heats up the air bubbles, which makes the air bubbles get bigger. The air bubbles push against the sugar and water and the marshmallow gets bigger.

When you take the marshmallow out of the microwave it will cool down. This makes the air bubbles shrink. Some of the water has evaporated in the microwave. The sugar cools down and hardens. This is why the marshmallow gets dry and crunchy.

Curriculum information

Sign up for the newsletter
Sign Up For The Newsletter
Want to get the latest science news from Planet Science straight to your inbox? Sign up now!