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Catch Their Attention with Some Eggs
Most students will sit up and take notice when you bring eggs into the classroom. Maybe they're hoping you'll drop one and make a spectacular mess, or perhaps they're just intrigued by the introduction of an unusual teaching tool. Whatever the reason, these experiments are sure to be a hit any time of the year. They're especially great when you can tie them to current events, such as Easter or a trip to a farm, but they're loads of fun absolutely any time at all.
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You'll need two eggs, two clear glasses or other containers large enough for an egg to float in, five tablespoons of sugar, and a permanent marker. Mix the sugar into one container of water that you want to float the egg in. Try the trick out with your containers, and adjust the amount of sugar as needed to make the egg float.
In its simplest form, just have the kids speculate about whether an egg will sink or float. Tell them that your eggs are quite intelligent and that they will sink or float on command. Write 'sink' on one egg and 'float' on the other to prove it. Put the sinking egg into the container of plain water and put the floating egg into the sugar water to prove your point.
If you'd like to dress up the trick a bit (or use it to introduce other concepts), you can change the words you write on the eggs. Have students share discouraging events before sinking an egg, and encouraging events that have happened to them before you float the other one. Or, if you need to force a decision to go the way you want, announce that the eggs will make the choice for the class. Write the desired outcome on one egg and the alternative on the other egg. Put the alternative into the plain water and the egg with the desired outcome into the sugar water, and the floating egg "wins"!
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Materials for this experiment include eggs, an egg carton, and some heavy books like encyclopedia volumes. If you'd like some added drama, you can also bring cleaning supplies (though you won't need them). Egg shells are surprisingly strong and most people are astounded at how hard it can be to squash an egg. The secret is to avoid putting weight on a single point, but rather to distribute the weight evenly. Nonetheless, be sure to try these experiments out before you use them in class!
Ask for a volunteer who is strong enough to squash an egg with his or her bare hand. Most kids are convinced that this is an easy task, so be prepared for a lot of volunteers. Make sure your volunteer removes rings and grips the egg in the fist with fingers curled around it evenly. No finger should put extra pressure on the shell, or it really will break. It's impossible to break the shell if pressure is applied evenly.
You can also put four eggs in the corners of an egg carton and then place books one at a time on top of them. Keep the weight evenly distributed and the eggs will not break.
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This is perhaps the most spectacular trick of all, but it takes a bit of preparation. Soak an egg in a jar of vinegar for a day or two, and the shell will completely dissolve, leaving the fragile membrane holding the liquid in place. If you are careful, or possibly if you use a spoon, you can pick up the wiggling, jiggling mass to show off your shell-less egg. It's a great lead in for discussions about exoskeletons in science, or about how to handle teasing or bullying when you want to teach interpersonal skills.