Eggshell domes can support several books. How many can you stack?
Credit: Mary Bagley.
Did you know that Easter eggs are wonderful materials for a little fun science? Try some of these fun science activities and find out how interesting your Easter eggs can be!
No. 1: Stronger than you think …
You may want to try this over the kitchen sink or place the egg in a zippered plastic bag.
To test the strength of an eggshell, place a raw egg in the palm of your hand. Squeeze the egg in your palm using an even pressure. Next, put your thumb and index finger on the ends of the egg and squeeze. Can you break the egg this way?
For the second test you will need four raw eggs; it’s best if they are close to the same size.
- Carefully crack the small end off of the eggs and empty the contents into a bowl. You can use the egg whites in the protein experiment (see below) — or have an omelet for lunch. Rinse the empty bottom half shells and leave them on a paper towel to dry.
- Use small scissors to trim the broken edges of the egg shells so that you have four egg shell “domes” all the same size. This needs to be done very gently so that you don’t make cracks in your test subjects.
- Arrange your shell domes on a flat surface into two rows of two shells apiece.
- Rest a large book so that it rests evenly on top of the shells. How many books can you pile on top before the shells give way?
Questions to think about:
- Did the strength of an egg surprise you?
- How is the shape of an egg related to its strength? (Hint: The oval shape of an egg is kind of like two dome shapes put together.)
- Could just one eggshell dome hold up as many books as your arrangement of four eggs?
- How can a heavy hen sit on a nest full of eggs without breaking them?
No. 2: Swimming Eggs
First, take a raw egg and place it gently in a glass jar. Fill the jar with water and set it aside for at least 15 minutes. Observe the egg through the glass. You should see bubbles forming around the egg, evidence that gases are moving through the shell through tiny openings invisible to the naked eye.
Now, when you placed the egg in the jar of water, it remained submerged. Eggs do not float in fresh water. Carefully remove the egg and add 3 tablespoons of salt to the water in the jar. Stir to dissolve the salt and gently replace the egg. Does the egg float now? Continue to add salt to the water until the egg floats at the surface.
Questions to think about:
- Why would it be important for eggs to allow air to enter and carbon dioxide to exit through the shells?
- Why did adding salt to the water allow the egg to float?
No. 3: Spinning Eggs
In the first and second experiments, we explored the strength of eggshells and the density of eggs using salt water. In these experiments we will look at inertia and proteins.
For this experiment, you will need one raw egg and one that has been hard-boiled. Mark the shells with a crayon so you will remember which has been cooked. Place both eggs, lying on their sides, on a smooth flat surface. Use your fingers to twirl the eggs until they are spinning rapidly, and then quickly use one finger to stop the motion. Be quick to lift the finger as soon as the egg stops moving!
Questions to think about:
- Which egg was able to spin faster before you stopped the motion?
- Which egg moved again after you stopped the motion?
- Which egg has more inertia? Inertia is a physical property of matter. It means that something will resist any change to its motion. If the object is not moving, you have to apply some kind of force to make it move. If the object is in motion you have to apply some kind of force to change its speed or direction. You applied a force to twirl the eggs and then applied a force to stop them from spinning. Why did one egg resist stopping?
(Hint: The liquid center of the raw egg was in motion as well.)
(Another hint: The one that resists changes to its motion has greater inertia.)
No. 4: Unfolding proteins
An egg has two edible layers inside of it, the yellow yolk and the translucent egg white or albumen. The albumen is made up of protein, water and vitamins like riboflavin and niacin. In a fertilized egg, the albumen provides the developing chick with protein and water, and then helps lubricate the inside of the shell when it is time for the baby bird to hatch.
- Crack two eggs in half over a bowl. Juggle the contents back and forth between the shell halves, allowing the egg white to run out into the bowl but catching the yolk each time. This is called “separating” the egg. You will not need the egg yolks for this experiment, only the whites. Try not to touch the egg whites with your fingers or allow any yolk to get in with them.
- Place the egg whites in a clean, dry mixing bowl made of glass or metal. Add 1/8-teaspoon salt and 1/8-teaspoon cream of tartar. Using a wire kitchen whisk rapidly beat (stir very quickly while lifting to let in a lot of air) the egg whites. In a few minutes, air will become trapped in the mixture forming soft white foam. You may want to use an electric mixer instead of whisking by hand as the foam becomes unstable if you stop for a break before it is done.
- As the mixture begins to foam, add a half-cup of superfine granulated sugar to the mixture. Be sure to add the sugar one or two tablespoons at a time, making sure the sugar dissolves completely.
- When you can lift a spoonful of foam and turn it upside down without losing any, your foam is done. It should form stiff peaks when you lift the spoon or mixer beaters out.
- Cover a cookie sheet with aluminum foil and drop spoonfuls of foam onto it one inch apart — like cookies. Sprinkle with crushed peppermint candy or colored sugar and bake in a 225-degree oven for about an hour and a half. Allow them to cool and then you can eat your science!
Thinking about the science
The albumen is made up of protein and water. Proteins are very long chains of molecules that are folded up. Beating the egg whites causes the proteins to unfold and spread out, trapping the air. In science, foam is a mass of gas bubbles trapped in a matrix of molecules. You have to be careful not to touch your foam with your fingers or allow any fat from the egg yolk into your matrix or the proteins won’t unfold properly and it will take too long to form the foam. This experiment also works best on a bright dry day. In humid conditions, the water in the air will prevent the proteins trapping air.
For more “egg”citing science, see: