Marshmallow and Cherry Science Density Layer Cake

Bake a little science cake for your love this Valentines Day. This experiment mixes a little kitchen science, candy science and physical science. And the end result of this activity is delicious.

To make a 3-layer density cake, you will need the following materials –

  • Cake mix (flavor is up to you, we used Devil’s Cake)
  • Bag of small marshmallows
  • 2 cans of cherry pie mix with whole cherries
  • Eggs
  • Oil
  • Water
  • Clear glass cake pan

Instructions –

  1. Prepare cake batter per box directions.
  2. Spray the bottom of the cake pan.
  3. Cover the bottom of the pan with marshmallows.
  4. Pour cake batter over the marshmallows.
  5. Layer the cherry pie filing on top of the batter. Do this quickly, as the marshmallows will start to float up almost immediately.
  6. Bake the cake according to box directions.

As the cake bakes, the marshmallows and cherries will switch places. You have to check in on the baking process to watch the science. The baking is the best part (besides eating the cake.) As the marshmallows rise to the top, they will melt and become gooey. During our experiment, the marshmallows completely melted and disappeared. You may want to try baking your cake slower and at a lower temperature to preserve the marshmallows. As the cherries fall to the bottom, they will only be visible after cutting the cake or looking through the clear bottom.

 How does this work?

The answer lies in density. Density is defined as mass divided by volume or the amount of stuff in a certain amount of space. Marshmallows are sugar puffed up with air. They are much less dense than the cherries. The marshmallows are less dense than the cake batter too, so as the batter naturally descends to the bottom of the cake pan, the marshmallows rise. The cherries are the most dense, so they fall to the bottom.

What other ingredients can you use to switch places in this yummy experiment?

This experiment was developed by former teacher and Story Time Slime speaker Julie Gintzler as a 100-day activity with her class. She lined 100 marshmallows on the bottom of the cake pan as part of the celebration. 

3 replies
  1. Carla
    Carla says:

    Very cool! Will be trying this. Any idea if regular thawed cherries would work instead of pie mix? Seems the same thing for density but would hate to disappoint my young audience 🙂

    • Susan Wells
      Susan Wells says:

      I would think the thawed cherries would still work. It’s all about density and as long as the cherries are denser than the batter or marshmallows, it should be fine. You may want to do a trial cake just to make sure.

  2. Virginia Musci
    Virginia Musci says:

    I made a similar receipe called Strawberry Shortcut Cake. It uses thawed frozen strawberries mixted with strawberry jello. The batter is from scratch, flour, eggs, milk, crisco, vanilla. Minuature marshmallows on bottom as yours. This time it didn’t work. I tried it twice once in an dark pan and once in a glass pan. Marshmallows stayed on the bottom and burnt black and the strawberries stayed on the top. This never happened while in PA now I live in SC. Help!


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