Stalactite/Stalagmite Experiment

We found this simple and fun experiment in, The Everything Kids Science Experiments Book.

Your child will need the following items-

  • one large glass
  • two small glasses
  • tap water
  • a spoon for stirring
  • Epsom salts
  • cotton string
  • wax paper
  • paper towels
  1. Prepare a space for this experiment where it can sit untouched for at least a week.
  2. Lay down a layer of paper towel topped by a layer of wax paper. (The paper towel makes clean up easier.)
  3. Have your child fill the large glass three-fourths full of water.
  4. Add a generous amount of Epsom salts to the water. Stir with the spoon to dissolve. Keep adding salts until no more can dissolve and a little bit remains undissolved.
  5. Divide the saltwater into each of the two small glasses.
  6. Arrange the glasses a little bit apart from each other on the wax paper. Cut a length of the string, long enough for each end to rest in a glass and stretch across the space between each glass.
  7. Check the progress every day and watch what happens!



Hopefully you can see the difference from the picture on the top to the one on the bottom, a few days later. I’d have your child straighten the string more than we did, but it still worked out great. It’s really been fascinating to see the difference from day to day.

Here’s a video I found on Youtube. This lab can tie into learning about caves and also about icicles.

6 thoughts on “Stalactite/Stalagmite Experiment

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