Did you know that you can tell whether an egg is raw or boiled without cracking the shell? It is called the egg spin test and it is really easy and fun to try at home or in the classroom.
How to Tell if An Egg is Hard Boiled
My kids (and I) were excited to learn about this simple egg experiment which came in handy in our home recently. As we were preparing for some serious egg decorating, we lost track of which bowls contained raw egg or boiled egg.
Without having to crack an egg, we used egg physics to help us solve our problem in the form of the egg spin test.
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Egg Spin Experiment: Raw vs. Boiled Egg
I did a little research and found a simple way to figure out which of the eggs were boiled and which of the eggs were still raw with a simple spin an egg. This helpful egg hack is also a great way to teach a little science lesson for the kids.
Supplies Needed for Egg Spin Test
- Eggs – raw & boiled
- Flat surface
Egg Spin Test Instructions
Step 1 – Find a Test Surface
Place the egg in question on a flat surface.
Step 2 – Spin an Egg
Grip it between your thumb and fingertips, and then gently spin it. Emphasize “gently” with your kids, because a raw egg spinning off the table can get messy…I speak from experience!
Step 3 – Stop the Egg Spin
While the egg is spinning, touch the egg lightly enough to make it stop spinning, and then lift your finger off.
Results of Spin Test: Is it a Boiled Egg? Is it a Raw Egg?
If the egg is hard boiled:
If the egg is boiled, the egg will stay in place.
If the egg is raw:
If the egg is raw, it will amazingly start spinning again.
So what in the world is going on?
This Egg Spin Experiment Works Because of Egg Physics!
This is a perfect example of inertia and Newton’s Law of Motion:
An object at rest remains at rest, and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force.Newton
So, something in motion will stay in motion until acted upon by another force.
1. Egg and Shell Spin Together When Egg is Raw
The egg shell and its content are spinning along together. When you stop the egg from spinning, you stop the egg shell from moving, but the inside of the raw egg is liquid and just keeps spinning around.
Eventually, the friction of the egg shell will slowly stop the liquid center from spinning, and the egg will come to rest.
2. Egg Mass is Solid when Egg is Boiled
Inside the hard boiled egg, the mass is solid. When the egg shell stops, the center of the egg cannot move anywhere, so it is forced to stop with the egg shell.
Try this egg experiment with your kids, but before you explain to them how it works, ask them for a theory on why the raw egg or boiled egg spins differently.
- Eggs – raw & boiled
- Flat surface
- Set your egg on a flat surface.
- Gently grip the egg between your thumb and fingertips and twist to gently spin the egg.
- While the egg is spinning, touch the egg lightly to stop the spinning and lift off your finger.
- FOR HARD BOILED EGGS: the egg will remain still. FOR RAW EGGS: the egg will attempt to continue spinning.
More Egg Science Experiments for Kids
Egg Drop Experiment for Kids
One of my favorite experiments in 6th grade science was the Egg Drop Experiment! Our teacher gave us almost two week’s worth of class time to work with a partner and research the best way to safely contain our raw egg so that it wouldn’t break when dropped from the stairwell of the top floor of the school.
See Kids Activities Blog egg drop challenge ideas that work great for homeschool, classroom or the science fair.
- Squeeze egg in hand experiment shows the balance eggs have between being strong and being fragile.
- How to make scrambled eggs inside the shell.
- Egg in vinegar experiment to make a naked egg.
- Hatching supermarket eggs?
- Did you know that traditional paints were actually egg paint?
Were you able to use the egg spin experiment to see if your egg was raw or boiled? Did it work?