We recently went on vacation to Carlsbad Canyons in New Mexico. My kids loved seeing so many stalactites and stalagmites. Through the Junior Ranger Program they learned the difference between the two. Stalactites hold tight to the ceiling while stalagmites might reach the ceiling. This science experiment is fun to watch each day as the crystals grow a little more and a little more.

Grow Your Own Stalactites and Stalagmites

Supplies Needed: 

• 2 glass jars
• spoon
• shallow dish or lid
• 2 paper clips
• baking soda
• 3 feet of yarn
• hot water
• large pitcher or mason jar
• food coloring

Instructions:

1. Place the dish in the middle of the two jars.
2. Fold the yarn in half and in half again. Twist the yarn tightly. 
3. Take the two paperclips and attach one to each end of the twisted yarn. 
4. In a pitcher or mason jar combine hot water with baking soda. Keep adding baking soda a little at a time until the baking soda will not dissolve anymore. Now you have made a concentrated solution.
5. Pour the solution from the mason jar into each smaller glass jar. Keep the left over solution as you will need it later. Making a new solution later will most likely be of a different concentration which could make the stalagtites and stalagmites break.
6. Wait and watch for a few days as the stalactite crystals appear. As the solution in each jar lowers add more from the pitcher to top it off.

After a few days it will look something like this.

My kids thoroughly enjoyed this experiment. We added red dye to the concentration to make it even more fun and the growth visible. Here’s another hint: If you want to speed up the process dip the yarn into the solution.