Are you looking for a fun and engaging way to introduce solutions and crystallization to your students? Maybe you are looking for an Easter-themed activity for your next science lesson? This experiment allows your students to grow really cool and colorful crystal geodes using egg shells and a few basic household products you probably already have on hand.
To open the lesson, display pictures of mineral crystals or geodes. Explain that in this experiment they will be growing similar crystals from salt (solute) in water (solvent).
This activity will help your students understand these three types of solutions using a given solute (salt) and solvent (water):
Your students should also understand that a geode is a rounded, hollow rock cavity that contains crystals or mineral deposits that form through the process of sedimentation. Explain to your students that sedimentation occurs when solute is dissolved in solvent and then upon evaporation, the solute is left behind and accumulates in the form of crystals.
This experiment uses a supersaturated solution, which is a solution that holds more dissolved solute than it would normally hold at room temperature by increasing the temperature of the solvent. When making these crystal geodes, you will heat the water to boiling, dissolve the Epsom salt, pour into your egg shells and then allow the supersaturated solution to cool and evaporate to grow the crystals.
Students may work either independently or in small groups to design and create a crystal egg geode and then observe and compare the growth of the crystals over the period of a week. Using small groups will allow for the purchase of fewer materials as well as student collaboration and differentiation. Students may record their observations in a lab notebook through the use of sketches, data tables and graphs.
- Have your students experiment with other solutes such as sugar, baking soda or table salt to see if they get the same result.
- Compare the size of the crystals at room temperature versus refrigerated.
Need a rubric to help assess your students through this fun and engaging crystal egg geode experiment?
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This is what you will need for this in-class or at-home experiment:
Egg dye (optional)
Small paint brushes or Q-tips
Toothpicks or wooden stirrers
Stove or hot plate
Step 1: Crack the egg at the narrow end and carefully make an opening the size of a quarter. Empty the contents of the egg into a bowl.
Step 2: Rinse your egg shells in a bowl of hot water. Rub your thumb on the inside of the egg shells to remove the membranes (there may be more than one). Allow the egg shells to dry.
Optional: Dye the egg shells using egg dye as directed on the box. Allow to dry.
Step 3: Carefully set the egg shells inside the egg carton and using a paint brush or Q-tip, coat the inside of the egg shells with a thin layer of craft glue.
Step 4: Apply a thin base-layer of Epsom salt crystals to the inside of the egg shell. Let the glue dry completely (this make take some time).
Step 5: Boil 1 cup of water using a stove or hot plate. Carefully remove from heat and then add ½ cup of Epsom salt. Stir until all of the salt is dissolved. You have now made a supersaturated solution. It should be thick.
Step 6: Pour the supersaturated solution into the egg shells using a ladle, filling them to the top.
Add a drop of food coloring to each egg and mix using a toothpick or wooden stirrer. Allow the egg shells to sit in the egg carton at room temperature in a safe place where they will not be knocked over or disturbed.
Step 7: Monitor your crystal geodes daily and record your observations. You should begin to see some crystal formation within a few days. Break open any hard, jagged crystal layers with a toothpick or wooden stirrer to allow the rest of the water to evaporate. After all of the water is evaporated, you will be left with colorful crystal geodes that are great Easter decorations for your students to take home.