Grow a Gummy Bear STEM Challenge

Have you ever wished your sweets were bigger? One easy way to grow a gummy bear or any other jelly type sweet is to put it in water. The candy will grow but might not taste as good!

Water moves into the gummy bear through a process called osmosis. Osmosis is the movement of water through a semi-permeable membrane from an area of high water concentration to an area of low water concentration. Water moves across the membrane until the water concentration is the same on both sides.

We designed an investigation to find out what happens to a gummy bear in plain water and salt water.

You’ll need

Gummy bears or other jelly sweet




Kitchen scales – optional

Small bowls or cups


Add enough water to two small bowls to cover the gummy bear completely. Each bowl should contain the same amount of water.

Add a tablespoon of salt to one bowl and stir well.

Weigh each gummy bear and record the weight.

Place one gummy bear into each bowl.

Keep a third gummy bear to one side. This is the control gummy bear.

Check every 30 minutes for about 3 hours.

Weigh the gummy bears again.

You should find that the gummy bear in plain water increases in size, and the gummy bear in salt water either shrinks or stays the same size.

The biggest gummy bear was the one soaked in plain water and the one at the bottom the control.

Extension Tasks

Add the expanded gummy bear to salt water and leave for several hours. It should shrink back down as water moves out of the gummy bear and into the salty water.

Set up an investigation with a series of bowls containing different amounts of salt. Watch what happens to each gummy bear!

What’s happening

Gummy bears and other jelly sweets are made mostly from water, gelatin and sugar. The concentration of water inside the gummy bear is low compared to outside the gummy bear, so water moves into the sweet by osmosis. This is why the gummy bear in plain water grows in size.

The concentration of the water in the salty water is probably similar to that inside the gummy bear, so this sweet does not increase in size. If you made the water extra salty, the gummy bear might shrink as water moves out of the bear into the water.

More science ideas

Learn more about osmosis with eggs! If you remove the shell of an egg with vinegar to reveal the membrane and place it in water, the egg will grow in size as water moves into the egg.

Build candy towers, a candy house, try some candy chromatography and more with my collection of candy science experiments.

Last Updated on February 15, 2024 by Emma Vanstone

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