Incredible Growing Gummies!

Gelatin contains long protein molecules that tangle together to trap water molecules. Because gelatin absorbs so much water, candy containing gelatin acts like a sponge. That’s what makes “The Incredible Growing Gummi Worm” one of our favorite candy experiments.

Soaking gummi candy for two days can make it grow twice as long. As the gelatin molecules form bonds, cross-linking like a jungle gym, they trap water molecules between them.

To turn a gummi worm into a “gummi snake,” fill a flat dish with water and drop in a gummi worm (or several). Set aside a dry gummi worm for later comparison. Check back every few hours to see your gummi worm growing, since it can continue to absorb water for up to two days.

Once your gummi worm has grown to its full length, you can perform tests to see how much it grew.
  • Use a ruler to measure the length of the giant gummi worm, then measure the dry gummi worm and compare.
  • Weigh it and compare its weight with a dry gummi worm. Be gentle, because a water-engorged gummi worm becomes fragile and splits easily, like Jell-O. Try moving it by tipping most of the water out of the dish, laying down some plastic wrap, and sliding the gummi worm onto the plastic to weigh it. Then weigh a dry gummi worm and subtract it from the weight of the giant gummi worm. The remainder is the weight of all the water that was absorbed.

You can also try this activity with other gummi candies, like fruit snacks or Life Savers Gummies. Check the ingredient labels to make sure that your experimental gummies do contain gelatin. Gummi candies without gelatin, like Swedish Fish, don’t absorb extra water.