Dissolving Peeps Experiment: STEM Activity for Eastertime -

Who’s up for a fun STEM activity for Eastertime? The next time you’re at the grocery store, pick up a package of marshmallow Peeps! Then, do the Dissolving Peeps Experiment with your kids. Feel free to adjust the experiment to try other liquids, other additives, and other candies!

Scroll to the bottom for a free download!

Disclosure: I get commissions for purchases made through affiliate links in this post.

Supplies for Dissolving Peeps Experiment

6 cups or glasses
pieces of paper and pencil to label each glass
a timer
6 cups water
½ cup sugar, divided
½ cup salt, divided
6 marshmallow Peeps

Instructions for Dissolving Peeps

Place 1 cup of cold water into three different cups. Into one cup, add ¼ cup sugar, stirring until it is dissolved. Into the second cup, add ¼ cup salt, stirring until dissolved.

Heat the remaining 3 cups of water until hot.

Place 1 cup of hot water into three different cups. Into one cup, add ¼ cup sugar, stirring until it is dissolved. Into the second cup, add ¼ cup salt, stirring until dissolved.

Place one marshmallow Peep into each cup of water. Set a timer for 2 minutes.

When the timer goes off, check the Peeps and make note of which have changed on your blank form (see below for a free download).

Continue checking the marshmallow Peeps every 2 to 5 minutes, making note of the changes.

Discuss which liquids caused the marshmallow peeps to dissolve faster/slower and why.

What does “dissolve” mean? When a solid dissolves in a liquid, it becomes incorporated into the liquid so as to form a solution.

When the Peeps are added to the water, salt water, or sugar water, the sugar and other ingredients in the Peeps dissolve into the liquid. The liquids with higher acidity break the sugars down faster than the liquids with less acidity. And the hot water breaks them down faster than the cold water.