With the knowledge of triboelectricity, we can play a little game. Put some dried rice grains in a small dish. Then, wipe the plastic spoon with a sweater or wool cloth for a while. At this time, the spoon generates electric charge, which is attractive.

Put a small spoon * near the top of the plate with a small grain of rice. At this time, the millet is attracted by the charge and will automatically jump up and adsorb on the spoon. At this time, an interesting phenomenon is about to happen-the small grains of rice that have just been sucked on the spoon suddenly spread around like sparks in the blink of an eye. What is the reason?

The original charged spoon attracted millet for a short time. When millet is adsorbed on the spoon, the charge of millet adsorbed on the spoon is the same as that of the spoon. As charges of the same sex repel each other, the rice grains adsorbed on the spoon repel each other and all scatter.

2. Who will tidy up first

Mix the coarse salt and pepper noodles together, can you separate them again soon?

This game can be played by one person or several people at the same time. See who uses the best method and get it first.

The game is played like this: first give everyone a small plastic spoon, then put a spoonful of salt and half a spoonful of pepper noodles in front of each table. When ready, the referee can order the players to start grouping. Whoever finishes first will win.

This game seems more difficult. If you choose salt grain by grain by hand, you can't win. If you know a little about static electricity, you can easily win.

After hearing the referee's "start" command, the contestants rub the plastic spoon on the sweater or other woolen cloth for a while, and then gradually approach the mixture of pepper and salt. At this time, the Chili noodles will jump up and adsorb on the plastic spoon. In this way, you will quickly separate the salt particles from the pepper noodles.

This is because the plastic spoon is charged by friction, which produces attraction. Pepper noodles are lighter than salt, so they suck. Be careful not to put the spoon too low, or the salt particles will be sucked up.

Let's see whose rocket flies farther.

Before playing this game, each participant has to make a "compressed gas rocket". Specific practices are as follows:

Find a soft plastic bottle (such as an empty bottle filled with glue or an empty bottle filled with drinks), drill a small hole in the bottle cap, insert a plastic thin tube (you can cut off the nib of the waste ballpoint pen core to replace it), and then stick it with all-purpose glue. Find a straw with a length of 10 cm that can slide freely outside the plastic pipe, and stick four triangular colored papers on one end of the straw as the tail of the rocket; The other end is sealed with dough and shaped like a rocket head. When the dough is dry, the game equipment-compressed air rocket is ready for the game.

During the competition, the contestants stood side by side and put the "rocket" made of straw on the plastic pipe. After the referee gives the password, the contestants squeeze the bottle hard with their hands, and the "rocket" will fly to 10 meters away with a whoosh. Whoever flies the rocket far is the winner. You can also launch it several times in a row and add up the distance of each launch. Whoever is far away is the winner.

The launching principle of this rocket is as follows: the air in the bottle enters the suction pipe through the plastic pipe. Because the front end of the suction pipe is closed, the compressed air entering it expands and is sprayed to the rear end (open end) of the suction pipe, giving the suction pipe a forward force and the suction pipe flies forward.

4. soap boat

Split one end of a match or feather pole from the middle (the split length accounts for about a quarter of the total length), and put a small piece of soap in the split place, and a "small rowing boat" is made. Put this "small rowing boat" in the basin and it will automatically run quickly in the water.

Everyone participating in the competition should prepare the same number of "small rowing boats" and put them into the basin (preferably in the big basin; To be on the safe side, don't play this game by the pond. Who sees the "small rowing boat" with the slowest speed, give 1 minute; The penultimate place is 2 points ... and so on. After the first rowing competition, the second rowing competition will be held ... after the last round of competition, whoever has the most points will be the winner.

In this game, we can also compare who swims farthest in the rowing boat and who is the winner.

The reason why the "small rowing boat" can run in the water is that the soap embedded in the match gradually dissolves in the water, constantly destroying the surface tension of the water behind the match, while the tension in front of the match is not destroyed, so the water molecules behind the match are pulled forward by the water molecules in front of the match, and the "rowing boat" moves forward. Note that when the tension of the water in the basin is destroyed by soapy water, the "rowing boat" will not move forward, and the water should be changed in time.

5. Jet speedboat

When we have the following materials at hand, we can make a "jet boat" for the competition. These materials are: small metal iron box (flat iron box or metal soap box), empty iron pipe (or round iron box), two iron wires and several candle heads.

The production method is as follows: first, put some water in the iron drum, and be careful that the water quantity does not exceed one third of the capacity of the iron drum. Then plug the iron drum with a cover or something else to stop the water from flowing out, and then drill a small hole in the cover. Fix the iron drum on a small metal iron box with iron wire, and put two or three candle heads under the iron drum. After lighting the candle head, the water in the iron drum will boil after a while, and steam will be ejected from the small eyes to push the small iron box forward in the other direction. So the "jet boat" was completed.

If several children each make a jet boat like this, they can play the game of "regatta". When the participants' boats start to blow, they can put them into the water. When the referee gives the order, the ship can sail forward as soon as it gives up. Let's see which ship runs fastest.

In this way, you can make different kinds of small jet boats with different materials and play different games.

Skillfully move table tennis

Prepare a long table (desk, square table is also acceptable) and put several cans of table tennis upside down on the table. Contestants should hold the inverted bottle in their hands (be careful that the bottle mouth can't be blocked with anything) and transport it to the front together with the table tennis in the bottle. Whoever arrives first will be the winner. Whoever has the simplest method is the best winner.

It seems that the game is impossible to finish. As soon as I picked up the upside-down bottle, the table tennis was left on the table, not to mention it was difficult to stay in the bottle.

In fact, this game can be played. There is a clever way that you can easily transport the empty bottle with table tennis to the place you want to go. You can do this as long as you grab the bottle and make a regular circular motion on the table to drive the ping-pong ball in the bottle to rotate along the inner wall of the bottle. Because the ball produces centrifugal force when it rotates, when the centrifugal force is greater than the gravity of the earth on the table tennis, the table tennis will do inertial motion on the inner wall of the bottle and will not fall out of the bottle.

Of course, when you move the bottle, you must always keep a uniform circular motion. If you are fast and slow for a while, the table tennis will leave the bottle wall and fall out of the bottle.

7. Bananas that peel themselves

Before playing this game, prepare a banana, a wine bottle and some highly alcoholic liquor (alcohol is better).

We know that bananas in fruits are easy to peel, so if we succeed in this game, we can see with our own eyes how banana peels "spontaneously". Take a slightly overcooked banana and peel off the end for later use. Find a bottle with a mouth that allows banana meat to enter (it is easier to choose bananas that can meet this condition-that is, choose bananas that can enter the bottle), pour a small amount of white wine (or alcohol) into the bottle, light the wine in the bottle with lit matches or burning paper, and immediately put the end of the banana on the bottle mouth, so that the bottle mouth is completely blocked by banana meat, and the banana peel is placed outside the bottle mouth.

At this time, you will be surprised to see an interesting phenomenon: the bottle seems to have magic, desperately swallowing bananas and making a noise. Finally, the banana meat was sucked in by the bottle, but the banana peel "fell" and stayed at the bottle mouth.

It turned out that this was because the burning liquor exhausted the oxygen in the air, and the pressure in the bottle was lower than that outside, so the outside air pushed bananas into the bottle.

If the bottle mouth is not completely blocked after putting bananas, the game will not be good. In addition, if the game is not successful because the banana is not ripe, you can make two or three vertical cuts on the banana skin in advance, and it will be easier to make it again.

8. Gas Weightlifting Machine

If someone says that he can lift something weighing 10 kg to a certain height with one breath, you will definitely think that he is bragging: "How could this happen?" It's impossible! "

However, as long as I tell you a simple method, the exhaled air can completely lift the weight of 10 kg, and you can do it yourself. Try it yourself if you don't believe me.

Put a strong rectangular paper bag or plastic bag on the table, which is big enough to put two thick books in. Put a lot of books on it-take the thickest and heaviest book you can find. At this point, you can start blowing into the bag. It should be noted that the blowing port should be very small, so it is easier to blow and does not require too much effort.

Blow slowly and evenly. You will find that the air you blow out, after entering the schoolbag, will slowly expand with the schoolbag, and it is easy to lift many books on it. You will be excited at this time-it turns out that my breath has such a magical effect!

In fact, as long as the size of this paper bag or plastic bag is 10 cm× 20 cm (200 square cm), a force of 20 kg can be obtained by blowing air slightly larger than one atmospheric pressure. So it is easy to lift the weight of 10 kg.

9. homemade "air gun"

Many teenagers like playing with guns. Now, we make our own "air gun" and then use it to compete.

Prepare a metal tube or glass tube first (if you really can't find a metal tube or glass tube, you can use bamboo instead). The diameter of the tube is about 8 8- 10/0mm and the length is 6-8cm. Prepare another stick or pencil with a length of about 15cm. When these things are ready, there will be an "air gun", and the remaining problem is to find a "bullet". This problem is also very easy to solve, just find a potato or apple-cut the potato or apple into pieces for later use.

You will be disappointed with this "air gun": alas! What kind of gun is this? However, when you insert both ends of the tube into the potato chips, the potatoes will be embedded in the tube and block both ends of the tube. At this time, all you have to do is slowly push the potato chips at one end into the barrel with a stick or pencil, and aim the other end at the target you want to shoot. This "air gun" in your hand will pop up a potato bullet and shoot it at the target.

It turns out that this potato gun in your hand is a veritable "air gun". When you push potatoes into the pipe, the air in the pipe is compressed, and the compressed air rushes out from the other end, pushing the potatoes blocked at the pipe mouth at high speed. Attention! Be careful and agile when pushing with a wooden stick. As long as you aim accurately, you can hit the bull's-eye.

With the air gun, several children can play shooting games together. But pay attention to safety.

10. Whose balloon flies high?

If you buy a balloon carelessly, it will fly high in the blue sky. This kind of balloon contains hydrogen lighter than air. We can also make a balloon ourselves, but we can't get hydrogen easily. It doesn't matter. We can make a hot air balloon and let it fly into the sky.

Find a paper bag with light paper or 6 sheets of tissue paper inside; Then prepare glue (or paste), iron wire (or adhesive tape), cotton, alcohol (or highly alcoholic liquor).

First, weave a simple basket with iron wire, and the top of the basket is the same size as the paper bag. Then, hang the basket under the paper bag with some cut iron wires or some adhesive tapes. Put a tin lid (or other iron lid) in the basket, put a ball of cotton soaked in alcohol (or white wine) in it and light it: you can also find a lit solid fuel. At this time, the hot air balloon can be launched.

For the sake of safety, this game must be played in the wild. Be sure to pay attention to fire prevention

Although there is only a small ball of alcohol cotton here, the balloon can rise very high even without wind. Let's compare the children who take part in the game. Whose balloon rises highest?

If the hot air balloon is made beautifully, the effect will definitely be better. Cut 6 pieces of thin paper into the shape shown in the picture, glue the paper into a ball, stick a disc on it, and paint your favorite color on it, and a beautiful hot air balloon will be made. You can also tie a kite string to prevent the balloon from floating away.

Hot air balloons can fly to the sky because hot air is lighter than cold air, so hot air will take balloons to the sky.

1 1. Wonderful darts

Although Australian aborigines don't know science, they can make a wonderful and interesting weapon-darts. They hunt with darts. In fact, this kind of darts has already appeared in our country. The shape of the dart is very simple, just an arc board, but surprisingly, no matter which direction you throw it, no matter how hard you throw it, as long as the angle is right, it will eventually fly back to you.

Do you want to make a dart like this? It's simple. Find a piece of plywood or cardboard first. Draw a picture on the blackboard according to the shape of the picture. The two crutches are about 20 cm long. After drawing, use a small saw blade (or scissors) to cut (or cut) along the drawing line, and use sandpaper to round the corners.

You can play after darts are played. Hold one end of the dart with your thumb and forefinger and point the other end at yourself. As long as you throw the dart at a small slope with great strength, it will draw a curve in the air and then fly back to you.

If the darts can't fly back after being thrown, let's see if the problem is the darts first. If not, then you should readjust your throwing angle. As long as you throw it in the right way, it should come back to you.

You can also use toilet paper to make darts, or use a heavier material-iron plate to make bigger darts. See if they can fly back, too.

12. Interesting magnetic boat

Have you ever heard of a magnetic boat? It sounds mysterious. The magnetic ship does have an attractive mystery, because there is no practical magnetic ship sailing on the route so far! However, at the beginning of this century, a small boat was exhibited in Amsterdam. There is no power plant or propulsion system in it, and there is no wire to pull it. However, it kept spinning in the pool, which surprised the tourists. What forces keep the ship spinning? In fact, the reason is very simple. The boat is made of iron, and there is a strong magnet in a big flat plate under the pool where the boat swims. The big plate is driven by the motor and rotates slowly, and the boat swims along the moving route of the magnet.

Now, we can also play this little game. Find a piece of soft wood at random, cut several boats no more than 4 cm long, and nail a 2.5 cm long nail on the back of each boat; Make a small hole in the boat, insert a match, and then fold a paper triangle to make a "sail", and the boat will be finished.

Put the finished boat into a washbasin and slowly move the strong magnet under the washbasin (instead of the magnet in the earphone and speaker), and the boat can sail freely under your "navigation".

If several children each take a magnet and command their own boat, they can play all kinds of interesting "naval warfare" games.

13. Why is it rolled up?

Because of the gravity of the earth, everything falls from top to bottom; Water flows from high to low; Stones on the slope, roll down the slope. Can you imagine what it is like for an object to roll on a slope?

Below we can show you this interesting phenomenon. First make two cones with thick paper or thin cards, and then butt them together with glue (or paste); As shown in the picture, put a big book and a small book at a certain distance. Note that the back of the book should be up to keep it stable. Put two round chopsticks or sticks on the book. When you put it, let the higher-end round chopsticks be slightly separated from the lower-end ones.

Now, you can put the double cone you just made on the end of the stick near the book, that is, the lower end. At this time, you will be surprised to find that the bipyramid seems to have been "enchanted" and rolled up the hill along the "trajectory". What seemed impossible actually happened.

Is it really a double cone rolling uphill? Does the gravity of the earth have no effect on the bipyramid? No. You put the double cone on the stick and let it roll again. Watch carefully how the bipyramid rolls. You are sure to discover the mystery.

Look at the two ends of the double cone. They rested on two wooden crowbars that were close together. What happened? After rolling, because the distance between the two sticks is getting bigger and bigger, the double cone is actually downward. Take a closer look, is that right?

Pay attention to the height difference between the two books when playing this game.

14. Water droplet race

It must be interesting to hold a race for water droplets. Before the game, we should do some preparatory work.

Find a piece of oiled paper or plastic cloth as a runway for the water drop competition. It's best to have colored plastic sheets so that water droplets can run on them and we can see them more clearly (plastic sheets that are completely smooth and without bumps or wrinkles are needed). Find some books or bricks of different sizes, arrange them in order from high to low, and then spread them with plastic sheets, as shown in the figure. Such a "winding mountain runway" for small water droplets is ready. Don't forget to put a plate at the "finish line" of the runway to catch small water drops so as not to get the table wet.

First, try to drop a drop of water at the top of Panshan runway. You can see this drop of water rolling down the first slope, quickly climbing to the top of the second slope with inertia, and then sliding down the second slope with acceleration ... In this way, it rolled up and down on the winding mountain runway and rushed to the end.

After the test, you can start the game of "water drop competition" with others. Everyone prepares a small teaspoon with some water in it. When the referee gives the first password, drop a drop of water on the runway. Whoever reaches the finish line first gets one point; Whoever drops more than two drops at a time will record a foul and the opponent will get one point. When the referee calls the second password and drops a drop of water ... after the last round, whoever scores more points will be the winner.

15. Let's see whose pronunciation box can make the lion roar.

The game is to use a paper box (or wooden box or white tin box) to make a sound device. This sounding device made of boxes of different materials will make different sounds. See whose box sounds like a lion's roar, and whoever wins-because the lion is the king of beasts!

This device that can make sound is easy to make, as long as you find some paper boxes (try other boxes), open a small hole in one side of the small box, then put half a pencil with a small rope in the box and put the small rope through the small hole. Find a piece of rosin and rub it back and forth on the string, just like rubbing rosin on the bow string of erhu, which makes the string rough.

At this time, you hold the box in one hand, and the thumb and forefinger of the other hand are rowing the rope, and you will hear a loud noise. Some sounds may be like the roar of a lion, and some sounds may be like the barking of a puppy. I hope your vocal device can make a roar like a lion.

You can also use boxes of different shapes and materials to make more audio equipment. Maybe when you row the rope, the walls of the box are shaking, and the noise will be scary!

16. Who made the "Qin" with a nice voice?

First, make a small musical instrument. Then, let's have a competition to see who can play the piano well. Pick a few good ones, and then we can "ensemble" and participate in cultural performances. When people hear deep music, they may think it is played by cello!

Find an iron box, a straw more than ten centimeters long, a pig urine bladder and a string. With all these materials ready, you can start doing it.

Wash the pig urine first, and then soak it in water for a few days. After taking it out, tie its central part to a slender straw head and tie the straw firmly. After tying, spread the pig urine on the can with a little water, and tie the pig urine tightly on the can with a string to keep the straw in the center of the can.

When the instrument is finished, you can try its tone. Wet your fingers with water (don't wet your hands with spit, which is unsanitary), and put a straw between your thumb and forefinger, so that the pig urine will vibrate up and down and make a low hum. If you do well, you can hear music like a double bass. With different cans, you can play different timbres. If several children cooperate well, it is entirely possible to play music.

17. Can you let the cigarette go down?

As we know, smoke usually rises. Now we can give it a try and see if it is possible to let the smoke go down.

First find a cardboard box for shoes (or snacks), a candle, two glass covers on kerosene lamps, and a piece of waste kraft paper.

It is not difficult for rural children to find the glass covers on two kerosene lamps. In case you have used the electric light there and can't find the glass cover at the moment, you can use two metal tubes (old chimneys used on the heating stove), but the observation effect is not as good as the transparent glass cover.

The paper box cover is provided with two holes slightly smaller than the diameter of the glass cover or metal cylinder. Place candles and two lampshades as shown in the picture. Please note that the candle should be placed directly under one of the glass covers. Light the candle, cover it, and be careful not to let the candle burn the carton. At this time, light the kraft paper with a match and take the smoking kraft paper to the top of the right lampshade. Soon, you will see smoke coming down-smoke from burning kraft paper enters the box from this glass cover and comes out from another lampshade.

It turns out that warm air is lighter than cold air. After the candle is lit, the air above it is heated to make the air rise and rise out of the lampshade. But the air must be replenished from below, so the air can only enter from the entrance of another lampshade. The force of air entering the lampshade is enough to suck smoke in, so we can see the "abnormal" phenomenon of smoke falling down.

18. Happy Little Swan

You must like this beautiful little swan. Its graceful posture when swimming is really admirable. We can make a swimming swan by ourselves, and then put our swans together to see who can do best and swim best.

Prepare the following materials before making a swan: several corks, two long needles for sewing quilts, some paper, glue, resin glue and a piece of camphor.

Pass two parallel and vertical long needles through a slightly larger cork, and then insert four small corks with similar sizes at both ends of the needles to form a cross (as shown in the figure). This cross-shaped shelf should be made as small as possible, and the width should not exceed 5 cm. Draw a lovely white swan with white paper (it is best to draw swan patterns on both sides of the paper) and stick this lovely swan on the cork in the middle. Carefully divide camphor into four small pieces and stick it under four small corks with resin. The cygnet that can swim is ready.

At this time, as long as you put this little cross into a basin of water, you can enjoy the lovely little swan spinning and dancing in the water. If you put the cygnets made by several children into the water at the same time, it will be like holding a swan dance here, and you will feast your eyes and enjoy the lovely swans. What's particularly surprising is that these cygnets don't feel tired at all. They jump around the clock.

However, please note that no matter making or playing, you must pay attention to cleanliness, and you must not get the cork and camphor dirty, especially the oil. The basin full of water should also be washed with washing powder, otherwise the swan who loves cleanliness will not dance.

19. See who succeeds first

This science game is like this: the referee first gives each participant an article, including an empty glass jar, an egg, a piece of salt and water. Then, the referee announced the request: first fill the bottle with water, and then use these existing things to find ways to make the eggs neither sink at the bottom of the bottle nor float on the water. Whoever does this first will win.

It's not so easy to keep things suspended in water. This phenomenon only occurs when the weight of this thing is equal to the weight of the boiling water it discharges. If we children calculate the size of eggs, and then compare whether the water of the same size and the weight of eggs are the same, it is really too difficult for everyone. What shall we do? Don't worry, here is a little secret to help you solve this problem. Let me tell you the fact that the same amount of salt water is heavier than fresh water. In other words, the relative density of salt water is relatively high. Eggs can float in strong salt water, but sink in fresh water. Now that you know this truth, can you figure out a way?

As long as you put half of the water with a lot of salt dissolved in it in a jar, and as long as there is enough salt in the water, no matter how big or small the egg is, it will float on the salt water. At this time, you carefully pour water slowly along the wall of the can bottle until it is full. At this time, you can meet the requirements put forward by the referee and let the eggs suspend in the water.

Don't be quick to play this game, you must be original.

……,……,……,……,……

23. The magical "cannon"

Let's start making a cannon. This gun is too powerful. It can magically "blow out" the candle flame 1 meter away, and you don't need to fill any "shells".

Find a cardboard cylinder with two closed ends, and cut a round hole with a diameter of about 2 cm in the middle of the cover at one end. This round hole is the muzzle of the cannon. Find something else to make a gun rack.

Now, you can try the destructive power of this kind of cannon: put the lighted candle at a distance of 1 m from the cannon and aim your cannon at the candle. Tap the bottom of the barrel once or twice with your hand, and you will see that the candle is immediately "hit" by your cannon. If the candle flame just flashes, your aim is not accurate enough. As long as the aim is accurate, even a candle flame 3 meters away can be extinguished.

What's going on here? It turned out that the "voice coil" from the cannon blew out the flame of the candle. We can put some smoke in the cannon to observe this phenomenon. Please ask a smoker to blow a few mouthfuls of cigarettes through this round hole. Now put this gun flat and tap the bottom of the paper tube with your finger. You will see a beautiful smoke ring spouting from the round hole, and when it flies forward, it can keep its shape unchanged. If you shine a light on the smoke rings and observe them in a dark background, you can observe them carefully. You will see that the smoke on each cigarette ring is spinning around quickly, which is simply strange.

You must have never expected that pointing your finger at the bottom of the paper tube would have such an amazing effect. The jetted "voice coil" can make the air generate such a powerful rotating speed and force, and blow out candle flames where people can't blow.

24. "Magic Power" of Water Column

Fill the washbasin with half a basin of water and let a ping-pong ball float on the water. At this time, you fill a pot of cold water with a kettle and pour it on the table tennis table. You must think that table tennis that floats gently on the water will be washed away by the rushing water column. However, a strange phenomenon appeared: table tennis was constantly "jumping" on the water surface by the rushing water, but it stayed in place against the current and did not "escape" to one side. As the water level in the basin rises, the table tennis slowly floats, but it still does not leave the water column that impacts it. At this time, even if you let the water in the basin surge, table tennis is still reluctant to leave.

You can also put ping-pong on a square bench and play a "magic" game. Just pour the water first, then put the ping-pong ball where the water column splashes (put it there first and then pour the water, and the ball will be washed away), and then you can let go when the water column falls on the ball. At this time, table tennis will be "fixed" on the stool by the water column and will not be washed away. Moreover, if you slowly move the kettle back and forth, left and right, this "magic" table tennis will follow the command and move with the water column. Do you find it strange?

Why is table tennis "sucked" away by water column? It turns out that when water flows around table tennis, the air pressure around the ball becomes smaller. As long as the water flow around the ball changes, the air pressure around the ball will also change. Under this pressure, table tennis is constantly adjusted and always stays at the bottom and center of the water column and will not be washed away by the water column.

How wonderful the pressure of the air is!

25. Waterproof gauze

Can gauze be waterproof? This question is simple, but not everyone can answer it correctly. It seems that the gauze is so carelessly woven and the mesh is so big that it is impossible to use it to "waterproof".

Let's have a try.

First find a bottle, put a bottle of water in it, then cover the bottle mouth with gauze, and tie the gauze tightly to the bottle mouth with string or rubber band. At this time, turn the bottle upside down and try to see if the water in the bottle will gurgle out.

Yes, water doesn't leak out-gauze can be waterproof. It blocked the water in the bottle and didn't let a drop go.

What is the reason? Gauze is waterproof for two reasons. First of all, air pressure is at work. Second, because the surface tension of water is at work.

The air pressure is very high, which can completely support the gravity of the water pressing on the bottle mouth, so the water will not leak downwards. In addition, the surface of water is like a layer of elastic skin, and the molecules on this layer of "skin" are tightly attracted by the molecules under the water surface, wrapping the water and preventing it from running around casually. The cloth umbrellas and raincoats we use are waterproof, and it is also because of the great surface tension of water droplets that it is not easy to enter the inner layer of umbrellas or raincoats.

In fact, the game you just played is a bit like a valve-it's easier to get in than to get out. Do not believe me, you pour the water out of the bottle, cover it with gauze, and then put it under the tap to receive the water, and you will see the water enter the bottle. When the water in the bottle is almost full, if you turn the bottle upside down, the water in the bottle will still not come out. Can you figure out what this is?

If you are interested, you can search "60 Science Games" and download it. Take a closer look ~ ~ ~ It may help you ~ ~