How to Grow Crystals on a String Overnight

Create beautiful crystals overnight using simple household ingredients and string in this easy science experiment for kids.

1. Gather Your Materials. You'll need: 1 cup of very hot water (adult supervision required), 3-4 tablespoons of table salt or Epsom salt, 1 piece of cotton string or yarn about 6 inches long, 1 clear glass jar, 1 wooden spoon for stirring, and 1 clothespin or pencil to hold the string. Make sure your jar is clean and your string is cotton or natural fiber, as synthetic materials don't work as well.
2. Create Your Crystal Solution. Have an adult carefully pour the hot water into your jar. Slowly add the salt one tablespoon at a time, stirring well after each addition. Keep adding salt until no more will dissolve and you see some grains sitting at the bottom. This creates what scientists call a 'supersaturated solution' - it's holding more salt than it normally could at room temperature.
3. Prepare Your String. Tie one end of your string to a clothespin or pencil. The string should be long enough to hang into the solution without touching the bottom of the jar. For better crystal formation, you can wet the string first and roll it in a little dry salt to give the crystals starting points to grow on.
4. Set Up Your Crystal Garden. Lower the string into the salt solution, making sure it doesn't touch the sides or bottom of the jar. Rest the clothespin or pencil across the top of the jar to hold the string in place. Place your jar somewhere it won't be disturbed overnight - a counter or table away from vibrations works perfectly.
5. Watch the Magic Happen. As the solution cools overnight, the salt molecules will start clustering together and forming crystals on your string. In the morning, you should see beautiful crystal formations hanging from your string. If you want bigger crystals, you can leave your experiment for several days, but change the solution every 2-3 days to prevent bacteria growth.