"Egg-citing" Science!: Experiments Using Eggs

With spring upon us, many of our students will soon be partaking in the age-old traditions of coloring eggs and community egg hunts. While eggs can be great for dying and hiding around this time of year, most people don’t realize that they can also provide a wealth of “egg-citing” science – and now is a great time to take advantage of all the leftover eggs many students will soon have at home!

One of my favorite demonstrations involves using a hard-boiled egg and a glass juice bottle to teach the concept of air pressure. First, you need to find a glass bottle with a wide mouth (1.5 to 2 inches works well) and challenge students to come up with ways to get a hard-boiled egg inside it (make sure the egg is peeled). It will soon become obvious that the egg won’t fit; most students will declare the task impossible without destroying the egg.

Next, use a match to light a piece of paper on fire and drop it into the bottle. Quickly cover the bottle mouth with the egg and watch what happens. The egg should start to wiggle around as the flame inside the bottle goes out, and the egg will “magically” drop into the bottle! If this doesn’t happen right away, try using a slightly smaller egg or greasing the inside lip of the bottle with vegetable oil (it’s a good idea to practice before doing this with students).

So how does this work?  Most students think the egg is somehow “sucked” into the bottle, but in reality, you’re creating a partial vacuum when you place the flame in the bottle and seal the opening with the egg. In order to understand how this happens, your students will need a basic understanding of molecules.

Solids, liquids, and gases are made up of molecules. In a solid, the molecules are tightly packed together, while gas molecules are much further apart. Inside the bottle, the burning paper heats the molecules of air and causes them to move far away from each other (heat causes things to expand). Some of the heated molecules actually escape from the bottle (remember the wiggling of the egg?), and when the flame goes out, the molecules of air in the bottle cool down. This cooling causes them to move closer together (cooling causes things to contract), making space for more molecules. With the extra room available, the pressure of the air molecules outside the bottle is so great that it pushes (rather than sucks) the egg into the bottle. Now you can truthfully explain to your students that science never sucks!

Students will likely want to see this demonstration multiple times, and you can put a fun twist on it by sticking two or three birthday candles into one end of the egg. Light the candles and hold the egg to the mouth of the bottle with the candles inside of it, only this time, tip the bottle upside down.  The egg will still be pushed into the bottle, seemingly defying gravity!

For more “egg-citing” activities, try one of the following lesson plans.

Egg Lesson Plans:

Egg Fun

Students learn about eggs, then conduct a few quick experiments dealing with the physical properties of eggs.

Egg-travaganza: Learning about Eggs and Chickens

In this lesson, students learn about caring for chickens and nutrition facts about eggs. They then complete several activites in which they take part in egg discussions, judging, dyeing, and hunting.

How to Float an Egg  

Students take part in a "float or sink" activity, then write down their observations on a handout. Then, students learn about density and boyancy, and come up with hypotheses about how many teaspoons of salt needs to be added to a cup of water to make an egg float.