How to Make Hanging Crystals?

BY ON Oct 5, 2012
Easy science experiments for kids

Growing Hanging Salt Crystals is a great science activity for kids to explore!


During the school holidays we took our girls to see a cave.  It was an amazing experience for them and aroused so much curiosity and questions.

I believe in embracing their interests and curiosity and exploring them further.


The stalactites, stalagmites and crystals (calcium sculptures) inside the cave were amazing and the girls were completely in ore of this.  These stalactites and stalagmites are formed by water dripping or flowing from fractures on the roof of the cave.  To try and imitate  this we set up an experiment to grow salt crystals hanging from a string of wool.


What you will need?


You will need two jars, a string of wool, water, two paper clips, small plate and bi-carbonate soda.  We also set up a table to write our observations down each day for 1 week.

  1. Fill two jars with hot water.  Stir in about six teaspoons of bicarbonate soda, until no more will dissolve.  When a layer forms at the bottom of the jars, this means no more will dissolve.  This was fun to watch as the water fizzed and bubbles formed in the jar, a bit like opening a bottle of soft drink.
  2. Tie a paper clip to each end of the piece of wool and place each end in each jar.
  3. Leave the jars for a week.  Crystals will grow along the wool and hang down over the place.

What is Happening?

The wool soaks up the mixture.  When the water evaporates, all that is left are the bicarbonate soda crystals (Salt).  The hanging crystals are formed when the mixture starts to drip from the wool and evaporate.  If you’re lucky, you might even get crystals that drip onto the plate and form columns… in caves.

Let’s Learn


Learning Experience from this activity:

  • Using descriptive words to express ideas and opinions.
  • Make connections with real life experiences.
  • Promote scientific thinking – predictions, observations, comparison, reasoning, data gathering, experimentation and evaluation.






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19 Responses to “How to Make Hanging Crystals?”

  1. Kelly says:

    Oh this is cool! We’ve made crystals before but differently to this, so will happily make more :-) Love the pic of your girls watching intently! Pinning now

  2. Penny says:

    I know I say I love your activities, and I do but this one ROCKS! I’m soooo doing this with the girls and I have everything I need already at home. Squeee! I love science! Pinned!

  3. Great activity.
    I still remember what my geography teacher taught me to help me tell the difference between stalactites and stalagmites: Stalactites hold on tight- Stalagmites might grow taller.

  4. I saw this on Pinterest and pinned immediately Janice!Love it and the pic of the girls is just so sweet! I just love your great ideas…i actually think my teen will like doing this one as she loves all things science!

  5. stephanie says:

    Great extension of a fabulous experience for the girls. I love the photo of the two of them looking at the crystals.

  6. Rebecca says:

    Love this activity! I remember doing this in school and would love to do it with my little one. Quick question, do you think it will work as well with cotton yarn? I don’t have wool, so I’m hoping it will work. Thank you for an awesome post! And you have beautiful girls!

    • Janice says:

      Hi Rebecca, thank you for your lovely comment! Yes, I think this would work just as well with cotton yarn as long as it is thick enough to absorb the salty liquid. Let me know how it goes! :)

  7. Christie says:

    You could take it a step further and set up a few different solutions – table salt, and sugar are both simple and grow decent crystals. Adding a drop of different food colour in each jar would also make interesting observations about how far along the string each colour goes!

  8. Angel kuhn says:

    Please tell me what bicarbonate soda is for the hanging crystals project?

  9. Caitlyn says:

    This looks like a great activity! Do you know if it would work with cold water instead of hot?
    I’m interested in trying it at Preschool :)

  10. can you do it with sugar

    • kitty says:

      If you want to do this with sugar tie your yarn onto a pencil and place over a tall glass of colored sugar water. You will have your own rock candy!!

  11. Sarah says:

    This is such a neat experiment! My daughter will love this. Thank you for the inspiration!

  12. Julia Borysova Ukraine says:

    This is an awesome resource for pre-school English teachers.

  13. Sally says:

    Does yarn work instead of wool?

    • janice Janice Davis says:

      Hi Sally, yes yarn will work for this activity. I am from Australia and we call yarn, wool here….they are the same thing. :) Enjoy the making the hanging crystals. :)

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