At-home experiment: growing crystals

6th grade students prepare their eggshells to grow crystals. 

After studying rocks and minerals at the National Museum of Natural History, Live It Learn It's 6th grade students get to grow their own crystals!  While these crystals will not be set in fancy jewelry, the process models--in just a couple of days--what nature does over thousands of years.  Students observe and record daily changes to their "geodes," and marvel at the beauty of salt.

You can easily grow a "geode" at home too!  Experiment with different types of salt (rock salt, table salt, epsom salt) and different colors and see how this affects the crystals.

Crystals after 1 week

Materials
½ eggshell             
1 handful rock salt     
½ cup hot water
empty cup
1 spoon               
2 drops food coloring
empty egg carton              
newspaper

Multi-colored crystals

                           
Procedure
Make the Crystal Solution

1. Cover your workspace with newspaper. 
2. Pour hot water into cup. 
3. Stir rock salt into the water until it stops dissolving and you see some solid at the bottom of the cup.

Grow the Crystals

1. Place the shell into the carton.
2. Add food coloring to the egg shell.
3. Carefully spoon the crystal solution into the shell until the shell is ½ full.
4. Set the egg carton in a place where it won't get knocked over.
5. Crystals will start to grow in several hours, and may continue to grow for several days.
6. Each day, check to see how the crystals are developing—you can even shine a flashlight on your geode to see the crystals.  Record your observations.
7. You may stop the experiment whenever your geode looks like it has enough crystals.  Pour out the solution and allow the geode to dry.