Here is the translation of the given content into English: "245 Fun Experiments to Develop Your Child's IQ" Note: The line breaks () are preserved as they are in the original text.

Author: Peng Zhengming, Wu Yunchang
Publisher:
Publish Date: 2006-08-01
Features:
4：How to Peel a Boiled Egg
Do you always have your parents peel eggs for you at home? Do you know how to peel a boiled egg? If not, let's learn how now.
Materials Needed:
- 2 eggs
- 1 pot
- 1 basin of cool water
Experimental Steps:
(1) Boil the two eggs together in the pot.
(2) After the eggs are cooked, remove both from the water. Place one in the cool water, while the other cools naturally.
(3) Once the eggs are cool, try peeling both. You will find that the egg placed in the cool water peels off very easily, while the one that cooled naturally is much harder to peel.
Pay close attention! Hehe, kids, be careful not to get burned!
Why does this happen? Here's the explanation:
First, when the egg is first immersed in cold water, the shell contracts directly due to the cold, while the protein cools down less and contracts minimally. At this stage, the main effect is the contraction of the shell.
Second, due to the differences in the thermal expansion and contraction properties of different substances, when the entire egg has fully cooled, the looser protein contracts more than the shell, resulting in a more noticeable contraction. This causes the protein and shell to separate, making it easier to peel the shell.
5：The Little Bottle Ate the Big Egg
Do you want to play magic tricks? Now, let me teach you a simple one. How can you fit an egg larger than the bottle's opening into the bottle? Wow, that sounds too exaggerated—can it really be done? It's that simple. Follow me, and you can do magic too.
Materials Needed:
- 1 glass bottle
- A little fine sand
- An egg larger than the bottle's opening
- 1 piece of cotton swab soaked in alcohol
Experimental Steps:
(1) Choose a bottle with an opening slightly smaller than the egg. Spread a layer of sand at the bottom of the bottle.
(2) Light a piece of cotton swab soaked in alcohol and drop it into the bottle. Then, place one end of the egg (the smaller end) against the bottle opening.
(3) After the flame goes out, observe carefully. You will see that the egg is slowly "swallowed" into the bottle's belly. Wow, it's truly unbelievable!
Do you know why this happens? Here's the explanation:
The burning alcohol heats the air inside the bottle, causing it to expand and some of the air to escape. When the egg seals the bottle opening, the air inside cools down after the flame goes out, resulting in lower pressure than the outside atmosphere. Under the action of atmospheric pressure, the somewhat elastic egg is pushed into the bottle.
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