What is the easiest way to make something by hand? To be different from others, the simpler, the better, hurry, hurry! ! !

.Who knows how to make small inventions

Come on, let us teach you something useful. The simplest: make a pen holder! ! Do you have any unused glass cups at home? Or drop a tea cup or something, try it, anything heavy enough to hold the pen will do. Find a nice piece of cloth or colored paper and make a dress for the cup. Kraft paper is also very good. Wrap it around the cup, measure it, and cut out a suitable piece. There should be more joints...

6. Please explain how to make a small invention!

Homemade Kongming Lantern (1) Cut pieces of tissue paper into the specifications as shown in the picture. Glue one side of the first piece of paper to one side of the second piece, and then glue the third piece, The fourth picture...glue them on in the same order until it forms a ball with both ends open and a diameter of about 60 centimeters....

7. Scientific and Technological Inventions

The simplest: make a pen holder! ! Do you have any unused glass cups at home? Or drop a tea cup or something, try it, anything heavy enough to hold the pen will do. Find a nice piece of cloth or colored paper and make a dress for the cup. Kraft paper is also very good. Wrap it around the cup, measure it, and cut out a suitable piece. Leave about an extra centimeter at the joint. Find some glue,...

8. Small invention proposal

I will tell you a simple method, stick paper on both sides of the DVD box, and write your name on the left Class schedule, write your motto on the right. Such a small production is ready. The above methods are for reference only! !

9. After a simple on-site location, the police found that the two accident vehicles were severely damaged and could not leave the scene quickly, which had caused severe congestion on the northern line of the tunnel. There was only one tractor at the tunnel entrance. .. ...It’s the first time for small inventions to enter the municipal competition. Don’t underestimate it. Second-year student Zhan Yiming can also make small technological inventions! On National Day this year, when traveling to Huangshan, he discovered the cableway...

I am at home, washing dishes, mopping the floor, wiping the table, etc. As long as I can do anything, I always take the initiative to do it. The thing I fear the most is mopping the floor. I got blood blisters on my hands after mopping a few rooms. Cabinets, tables and other narrow places are not easy to mop, and they cannot be mopped clean. Once, while mopping, I thought, it would be great if I had a pair of mop shoes that I could wear on my feet to mop the floor! So, I designed a mopping tool that is both light and does not bend over - shoe slippers.

Preparation method: 1. Shoe slippers are larger than the shoes you usually wear, so they are easy to put on your shoes.

2. Use rag strips as mop strips on the soles, and nail a thicker plastic bottom on the mop strips, which is both waterproof and durable.

3. Use cloth shell and waterproof cloth to make the shoe upper, and install a zipper on the back of the shoe upper to make it easy to put on and take off. Connect the upper and sole to make the slippers.

Completing a small invention is not as simple as "furrowing your brows and thinking about it". It needs to go through steps such as topic selection, conception and design, production, practical testing and improvement, and success.

The first step in making a small invention is to determine the object of the invention and consider what problem to study. This is topic selection. For teenagers, they should start from the reality of life they are familiar with and look for creative themes in school, family and surrounding life circles. For example, when you encounter some difficulties in study or life, you will definitely say: "It would be great if there was such-and-such a thing." The thing you want to invent can be used as the object of invention. However, when choosing a topic, students must combine their own knowledge level and design and production capabilities, and do not dream of inventions that are impossible to achieve.

After the genre is selected, the next step is to conceive and design. That is, based on basic scientific principles and experience, the form, structure, method and implementation plan of the topic object are designed. When conceiving, try to come up with as many design plans as possible, and then select the best structural plan based on feasibility and practicality. It is better to use simple materials, be clever and easy to implement, and have the least shortcomings.

After the idea is mature, you can start production. During production, existing conditions should be used as much as possible to produce exquisite works with little or no money. For some technical issues, you can ask teachers and parents for advice. Sometimes you can also find relevant manufacturers to help make some parts.

After the small invention sample is completed, it needs to be tested and improved in practice. That is, use the work for a period of time, discover problems during use, and solicit opinions from parents, teachers, and classmates to see if there are any improvements or unreasonable areas. Then, the opinions from all aspects are combined to improve the small invention. Almost every excellent little invention is "modified".

At this point, you will enjoy the joy of success. Next, you can apply to participate in youth invention and creation competitions at all levels, apply for patents, or submit articles to newspapers and periodicals. The application documents for the competition mainly include the application form, project description and supporting materials provided by the organizing committee. Among them, the project description content is: how is the topic of the invention discovered, how is the invention plan designed, and how is the invention work produced? How does this invention demonstrate novelty, creativity and practicality? What is your creative contribution? Suggestions and ideas for further improving the invention. Attach appearance drawings (preferably black and white photos), structural drawings, schematic diagrams and other necessary diagrams and information. Any small invention projects involving medical and health care products, new varieties of animals and plants, and nationally protected animals and plants must also provide certification materials from relevant departments.

Scientific inventions are something that everyone can do, and it is also an interesting practical activity. As long as everyone carefully observes the things around them, is good at discovering and asking questions, boldly explores, hands-on practice, and has the courage to break through the constraints of rules and regulations, there will be innovations and inventions.

Handmade science category requires adding essence

Yellow yarn dolls

Colorful yarn dolls are beautiful and cute, because it is your skillful hands and love that gave them beautiful Image, they will also be your best friends.

1. Materials and tools: various colored yarns, cotton or stretch batting, silk flower petals, various colored post-it notes, buttons, ribbons, double-sided tape, and scissors.

2. Take the emperor? Embarrassing Lu? 筭笤谥crumbs Huan? Huan? Lu? 駧? Duh? Coin color cut? Ant fold? BR> 3. Fold the velvet bundle in half at the tight place, with both sides Unfold it slowly and wrap a small ball of cotton inside.

4. After confirming that the cotton is completely wrapped in the wool, tie the lower part with a ribbon (use double-sided tape to stick the ribbon), and the doll's head and body will be separated.

5. Take a small piece of wool and tie both ends tightly. These are the doll’s hands.

6. Separate the body of the wool doll from the middle and put the doll’s hands.

7. After closing the body again, tie the bottom of the hand with a ribbon.

8. Use wool to braid a small braid. Of course, she can have whatever hairstyle and color you like.

9. Use the hanging thread in the middle of the doll's head to tie the braid.

10. Pass the silk flower petals and a button through the hanging wire in sequence, and cover the top of the doll's head. That is her hat.

11. Cut out the eyes and mouth on the sticky notes and glue them on the doll’s face.

12. These are the finished wool dolls. They can be hung on your bedside or on your desk lamp or schoolbag to accompany you every day.

Test how much rain it rained today

It’s raining again. Looking at the rainy scene outside the window, do you suddenly want to know how much rain has fallen on farmland, rivers, and streets? superior? Usually, when listening to the weather forecast, you often hear: "According to a weather station, how many millimeters of rainfall will there be today... So, what is rainfall? How is rainfall measured?

The depth of the water layer that falls from the sky to the ground and accumulates on the horizontal surface without evaporation, infiltration, or loss is called rainfall (in millimeters), which can visually represent the amount of rainfall at present. The common instruments used by meteorological observatories (stations) to measure rainfall are rain gauges and measuring cups. The diameter of the rain gauge is generally 20 cm. It contains a funnel and a bottle. The diameter of the measuring cup is 4 cm. Pour the rainwater in the rain gauge into the measuring cup. The scale on the cup can tell you the amount of rainfall that day.

If you don’t have a rain gauge on hand, don’t worry. You can make one yourself using some common utensils, and the effect is quite good. A porcelain bowl with a diameter of 20 cm, drill a small hole slightly larger than a corn kernel in the bottom, and then place the porcelain bowl on a jar without a lid (there is a glass bottle in the jar, the bottle mouth and the small hole in the bottom of the bowl Connect). In this way, the simple rain gauge is ready. After the simple rain gauge is completed, it can be placed at a height of 70 cm from the ground to receive the rainwater. After the rain stops, use a scale to weigh the water in the bottle. , 30 grams of water is equivalent to 1 millimeter of rainfall.

Rainwater falling from the sky is an important source of water on land. If it is not polluted, its water quality is almost comparable to distilled water. Rainwater collectors have been installed in some places. After some treatment, the collected rainwater can be used to water green spaces, clean vehicles, wash roads, etc. Do you have any tips on how to make full use of "water falling from the sky"? < /p>

The trumpet that "spits" flames

Take a can, cut off all the open ends of the can, and make a small hole about 2cm from the bottom of the can. Take another piece. Roll the hard paper (or horse manure paper) into a trumpet shape, insert the blowing port of the trumpet into the small hole of the can, and use Badger glue to secure the joint. No air leakage, because this is related to the success or failure of the experiment ( Use a knife to scrape the small holes on the can to make the surface rough and easy to glue)

Experiment (1): Light the candle, put the flame close to the bell mouth, and quickly press the can into the water. In the container, you can see that the flame of the candle is tilted outward, as if the flame is spitting out of the trumpet (Picture 1)

Experiment (2): Slowly press the can into the water to a certain depth. , quickly pull the can up, and you will see the horn that swallows the flame of the candle. ㄍ2)?BR>
The physical principle is: a certain amount of gas, under the condition of constant temperature, its pressure It is inversely proportional to the volume. When you press down quickly, the gas in the tank is compressed and the pressure increases. When it is greater than the external air pressure, the gas in the tank will blow out from the horn and the flame will deflect outward; otherwise, when you pull it up quickly, the internal air pressure will be less than the atmospheric pressure. , the candle flame is swallowed into the trumpet

Seven-starred ladybug

Materials: a spherical medicine box containing Chinese patent medicine; red or black watercolor pens or paints; pins.

1. Wash the medicine box, remove the smell of medicine, dry it, and take half of it for later use;

2. Use a red watercolor pen or red paint or paint to paint half of the medicine box evenly;

3. Place the painted half of the pill box under a fan to dry. Use a black watercolor pen or black paint to draw dots on the red background, and draw a semicircle on the edge as the head (see the picture for specific drawing methods). Take this semicircle as the starting point and place it in the middle of the pill box. Draw a slightly thicker black line;

4. Insert 2 pins on both sides of the head to serve as the ladybug's whiskers. In this way, a cute seven-star ladybug is ready.

A double cone that can roll upward

1. Materials: Thick paper cut into a circle (with a diameter of less than 15 cm), scissors, glue, a pair of chopsticks or two A longer thin stick, a big book, and a small book.

2. Cut the round thick paper in half, roll it into two cones with the center of the circle as the vertex, and glue them firmly.

3. Connect the bottoms of the two cones and glue them together to form a double cone.

4. Place a large book and a small book at a certain distance apart on the table with their backs facing up. Place two chopsticks or thin sticks on the book so that the higher end is slightly smaller than the lower end. Leave some aside. At this time, if you place the double cone on the end of the chopstick near the small book, you will be surprised to find that it will roll uphill along the track!

The principle is:

The center of gravity of the double cone is at the intersection of the line connecting the two ends and the center of the middle circle. Since the chopsticks are open, if you observe the double cone carefully At both ends of the body, they actually roll downward. On the surface, the end point of the double cone appears to be higher than the starting point, but its center of gravity is always moving downward. Remember, unless there is an external force acting on it, gravity will always keep objects moving toward the center of the earth, so don’t be fooled.

A balance for weighing air

Materials: paper, glue, candle, thin thread.

Production steps:

1. First cut 2 pieces of paper 34 cm long and 15 cm wide. Divide each piece into five parts as shown in the picture, of which the narrow part on the right is 2 centimeters wide and the remaining quarters.

2. Fold the paper strip into a square barrel shape according to the dividing lines, and use the narrow part 2 cm wide as the adhesive strip.

4. Press in the middle ends of both sides of the upper part of the square barrel, glue it, and glue a 20 cm long thin line in the middle, and press the fold line on the lower part to form a square barrel shape. This is the weighing bag of the balance.

5. Cut a 25 cm long paper strip and roll it into a thin stick. This is the weighing rod of the scale.

6. Tie the two weighing bag mouths downwards to both sides of the scale stalk, tie a thin line in the middle of the weighing rod, and carefully adjust the balance.

7. Place a burning candle under a weighing bag (be careful not to burn the weighing bag), and the weighing bag will immediately begin to rise. And the other weighing bag started to fall. This means that warm air is lighter than cold air! Why? Because hot air has a smaller relative density than cold air, it is lighter than cold air. Hot air balloons are made based on this principle.

The "Little Pig that Can Run"

It would be fun to make a "Little Pig that Can Run" by yourself in your spare time.

Material L: cardboard, yellow clay, rubber bands, string, color, paste, scissors.

Method: ① As shown in Figure 1, draw the graphic on the cardboard, cut it out, punch a hole at the "0", and fold it at the dotted line.

② Make a "mud wheel" with yellow clay (preferably plasticine).

③ Insert a single rubber band through the left and right holes of the "mud wheel" and tie knots on both sides to fix the upper rubber band.

④ Fix a string on the "mud wheel", thread the string around the middle of the wheel several times, and pass the thread end through the hole in the middle.

When playing, first lift the string from the top. At this time, the weight of the pig will pull the wheel to rotate backward, and the rubber bands on both sides of the "mud wheel" will be tightened in the opposite direction; then, Place the cardboard piggy on the table and put down the string. With the power of the rubber band, the small wheel will rotate forward, and the "little pig" will automatically run forward.

Auto-rotating paper

Prepare a small rectangular piece of thin paper (3 cm long and 1 cm wide) and a long sewing needle.

Fold the paper in half along its two horizontal and vertical midlines. Unfold the paper again, place the intersection of the two folds on the upright needle point (the needle is first inserted into the cork and fixed with the needle point facing up), let the needle point just hit this point, and keep the paper balanced on the needle point . Rub the two palms together to increase the temperature of the palms, and then slowly place the palms next to the paper (as shown in the picture below).

Note that the hand should be moved over gently, and the wind will not blow the paper down when the hand moves. At this time, the paper can be seen spinning. Slowly at first, then gradually faster. If you gently take your hand away, the paper stops spinning immediately; if you move your hand closer, the paper starts spinning again.

What mysterious force makes the paper rotate?

It turns out that due to the different temperatures of various parts of the human hand, the temperature at the fingertips is always lower than at the center of the palm; therefore, a stronger updraft will be created near the palm, and the force it exerts on the paper will be greater than that at the palm. The finger end is large, and the force can rotate the paper.

Cut and mold a chick out of sponge

Use the scraps of sponge, according to its shape, combined with the appearance of the animal, use your brain, use cutting, pasting and dyeing methods, You can create a small and exquisite animal work. Let's take making a baby chick as an example:

1. Materials

One piece of sponge, watercolor paint, two small beads, and Badgum.

2. Production method

1. Cut the sponge into a rectangular parallelepiped. On the rectangular parallelepiped, draw the body, head, feet (the feet can be larger) and the outline of the mouth. contour. (Figure 1).

2. Pay attention to the drawn outline (leaving a certain margin), and boldly cut out its side shape (Picture 2).

3. Trim the head, body, and feet from the front and back of the chicken, and cut out the chicken wings (don’t cut too deeply). When pruning, pay attention to keeping the chicken upright (Picture 3)

4. Starting from the overall shape, trim the parts carefully and remove large scissor cuts.

5. According to your preference, you can dye the whole or part of it. After drying, glue on decorative beads to serve as eyes (Picture 4). If there are several sponges of different shapes, you can follow the above method to design several chicks with different postures. A group of lively and cute chicks will make you fall in love with them

The magical paper bridge

1. Experimental materials: two cups, some cardboard, a heavy object (such as soap), paper knife, and solid glue.

2. Place two cups on either side and lay a piece of cardstock flat on top to create a simple paper bridge.

3． Give it a try and see how much weight it can hold? As a result, it collapsed as soon as a heavy object was placed on it.

4. Fold this piece of paper into a corrugated shape at intervals of 1 cm, and the new bridge deck is completed.

5. Set up the paper bridge again, and look, this time the heavy objects are placed firmly.

6. Cut the cardstock into many thin strips and roll them into cylinders.

7. Glue these cylinders side by side and what you see is a different kind of bridge deck.

8. This kind of paper bridge is also very strong and has a large load-bearing capacity.

Experimental principle: A flat piece of paper is very thin, and a small force thickness results in a small force. After folding the paper into a corrugated shape or rolling it into a cylinder, the thickness of the paper is greatly increased, and the bearing capacity is much greater. This kind of structure is often used in stress-bearing structures such as bridges and buildings. It is light and strong and saves a lot of material compared with solid structures. Think about it, what other structure can achieve such an effect?

Egg Jet Boat

1. Experimental materials: eggs, cardboard, thick wire, candle ends, straws, double-sided tape, scissors, pliers.

2. Cut a piece of cardboard 25 cm long and 15 cm wide, and draw folding lines according to the pattern. It will be made into a boat hull.

3． Fold the hull according to the folding line.

4. Stick double-sided tape on the extra cardboard at both ends of the boat, fold it inward, and stick it in place.

5. Cut a rudder?

6. Cut a vertical slit in the middle of the stern, insert the rudder, and thread two thick iron wires through the middle of the boat, 3 cm apart, with the middle part of the wire slightly bent into an arc.

7. Poke a small hole in one end of the egg and two small holes side by side in the other end. Blow air into the egg from one small hole to let the contents of the egg flow out from the other end.

8. Cut the straw into two 4cm long pieces (jet tubes), insert them into the two holes at one end of the egg to a depth of about 1cm, and seal them with wax.

9． After pouring water from the other end of the egg (note that the water level should be below the jet pipe), seal the opening with double-sided tape. This is a small boiler.

10． Now make the stove again! Place a candle head on the bottom of the boat (between the two wires) and light it. A bottle cap can be placed under the candle.

11. Place the egg boiler on the thick wire with the jet pipe horizontally backwards. After a while, the water boiled, a burst of steam spurted out from the jet pipe, and the boat moved forward in the water! If you turn its rudder to a certain angle, the boat will circle vigorously in the water.

Experimental principle: The steam continuously generated after water boils can only be discharged backward from the jet pipe, thus generating a force acting backward, and this force has a forward reaction force on the boat. So the boat moved forward. This is consistent with Newton's third law, which states that for every action, there is an equal reaction.

Ping Pong Doll

1. Let’s make another cute doll. She is also made of those small waste items around us. Just imagination and your little hands, Ping pong doll is your favorite.

Materials and tools: bath balls, various colored cardboards, table tennis balls, yarn, pom-poms, velvet strips, small items that can be used as eyes, double-sided tape, and scissors.

2. Cut a hole 1.5 cm in diameter in the middle of the table tennis ball.

3. Use cardboard to cut a trapezoid with a top width of 5.5 cm, a bottom width of 10 cm, and a length of 11 cm. Paste double-sided tape on one hypotenuse and glue it to the other hypotenuse to form a column. body, and finally use scissors to cut the upper and lower ends flat. This is the body of the doll.

4. Cut a small piece of nylon net on the bath ball, wrap it around the cylinder and stick it with double-sided tape.

5. Insert the upper end of the cylinder into the hole in the table tennis ball, and the doll's head will be connected to the body.

6. Cut a 10 cm long velvet strip, stick it on the back of the body with double-sided tape, and then bend it to make the doll's hands.

7. Use wool to braid a small braid.

8. Use double-sided tape to stick the braid on the ping-pong doll’s head, stick two pom-poms on the bottom of the cylinder to make the feet, and stick the eyes and mouth on the ping-pong face.

9. Cut a cardboard strip equivalent to the circumference of a table tennis ball, use double-sided tape to stick it on the head of the table tennis doll as a hat, and flatten the top with your fingers.

10. Stick a strip of double-sided tape on the middle and the top of the hat respectively, and stick the colored pom-poms on one by one as an accessory for the hat. If you like, you can also use flannel to cut it for her. A small bow tie is glued to the neck. Look, the ping pong doll is smiling at you.

New Year's small pendant

It's the Chinese New Year, and the students probably all received a lot of New Year's money. Have you ever thought that the New Year's bag containing the New Year's money can also be turned into a beautiful and festive small What about the pendant?

1. Materials and tools: 12 Lunar New Year bags, 1 Chinese knot, 1 piece of silk thread (thin rope), tape paper, double-sided tape.

2. First fold each Lunar New Year bag in half, then fold the four corners to the middle crease.

3. Attach double-sided tape to the bottom of each folded corner.

4. Loop the silk thread and tie a knot. One end of the tape paper passes through the silk thread and sticks to the silk thread. The other end is glued to the inside of a Lunar New Year bag (close to the crease). In this way, the hanging silk thread is fixed, and be careful not to expose the tape paper.

5. Glue 4 Lunar New Year bags with silk threads together, folded corner to corner. This is the top of the pendant.

6. Take another folded New Year bag and glue the Chinese knot on the inside like hanging silk thread. Then fold the four New Year bags including it and glue them together, which is the bottom of the pendant.

7. Now there are 8 folded corners on the top and bottom of the pendant that are not glued, so fold the remaining four New Year bags and glue them in the middle.

8. After the bottom and top are connected through four New Year bags, the pendant is completed. Does it look good?

The roaring little box

1. Experimental materials: a paper (wood or iron) box, a pencil, a piece of rope, a piece of rosin, colored pens, glue, and white paper .

2. Tie the rope in the middle of the pencil.

3. Rub the rope with rosin, just like the bowstring of an instrument, to make it astringent.

Four. Open a bream on one side of the box to wish you┕?Wish? ΡPersimmon Linzhao Xieyongmu 驩妗?BR> 5. Wrap white paper on the outside of the box and stick it with glue.

6. Draw a lion or other guy with a loud voice on the box, and the tail should be exactly aligned with the exit of the rope.

7. Hold the box with one hand, and use the index finger and thumb of the other hand to stroke the rope. Ah, you heard the roar of the lion... Experimental principle:

When the friction sound of the rope is transmitted to the box, its four walls will vibrate and make a sound. Using boxes of different shapes and materials to do this experiment will produce different sounds, sometimes the sound can be alarmingly high. The sound production of stringed instruments, such as violins, cellos, etc., utilizes this principle.

Rubber band guzheng

1. Materials and tools: an empty wooden box or cardboard box, a piece of plywood or a stronger cardboard, some rubber bands, and scissors.

2. Cut the plywood or cardboard into a right triangle, and cut a small gap every 1 to 2 cm on the hypotenuse.

3. Glue the cut right triangle in the middle of the empty wooden box, stretch the rubber band and put it on the box and the hypotenuse gap.

4. Pull the rubber band and try to see if you can play 1-2-3-4-5-6-7... Adjust the tightness of the rubber band to adjust the scale.

Auspicious pendants

The new semester has begun, and the students are happily together again. In your spare time, try to make a few small pendants, keep them for yourself, or give them to teachers and classmates to express a sincere wish.

1. Materials and tools: golden paper (can also be replaced by other colored paper), Chinese knot, KT blow molding board (can also be replaced by colored cardboard), thin wooden strips, thin wires, double-sided tape, Paper knife, scissors.

Periscope

Students, if you have a periscope, you can clearly see things in the distance. For example, if it is blocked by a tall person, you can also see things in the water like a submarine. Observe the same situation on the sea below. Interesting, isn't it? Let's do one now.

1. Prepare the production materials first: thick cardboard, two 10×7.5 cm small mirrors, scissors, double-sided tape, triangle ruler, knife, and pencil.

2. Cut the thick red card into a size of 31 × 40 cm. Draw lines on the cardboard as shown in the picture. The four parallel lines are 7.5 cm apart. The square with an "×" on the left is 7.5× The size is 7.5 cm, the square in the lower right corner is also the same size, and a circle with a diameter of 4 cm is drawn in the middle.

3. Cut off the square marked with an " Glue the cardboard into a long cylinder, and the square and circle just cut out form two small windows in opposite directions.

4. Take out the glass from the small mirror and stick double-sided tape on the four sides.

5. Glue the two pieces of glass inside the long cylinder at an angle of 45 degrees from the window. Note that the positions of the two pieces of glass should be parallel after gluing. Note that the window and the interior of the column should not be blocked.

6. Use double-sided tape to stick the cut square on the top of the long cylinder. The small periscope is ready. You can use it to see many unexpected things. The experimental principle is that since light is reflected by the mirror twice and transmitted in the periscope body (long cylinder) at the same time, your line of sight can be extended as long as your periscope body is made.

Write with "invisible" ink

In adventure novels, you can often read secret letters or treasure maps written with "invisible" ink... What about the protagonist in the book? Go through hardships and dangers to reveal the secret. Today we will learn how to write this kind of top secret letter...

1. Ordinary white paper, pen, lemon.

2. Cut a lemon in half. This is your "invisible" ink.

3. Press the pen firmly into the lemon pulp so that the pen tip penetrates the lemon juice. But not too much or it will drip.

4. Use this special ink to write your "top secret letter" on paper. Use more force when writing and make your strokes thicker. Lettering works best when written with a thick nib.

5. The lemon juice dries up quickly and nothing you write will be visible.

6. Use a lighter to slowly bake the written paper. Be careful not to burn the paper or your writing will be lost forever! During the heating process, the invisible writing gradually turns to brown and appears, and the letter is ready to be read!

Small phone

1. Experimental materials and tools: 2 paper cups (or empty cans), a long rope, colored paper, scissors, double-sided tape, and something that can be used as eyes Small round beads.

2. The two microphones of the small phone are cute cartoon friends. Let’s make them come alive first. First, use green paper to cut out the "parts" of a small frog - forelimbs, hind legs, eyes, etc.

3. Glue these parts to a paper cup to make it a little frog.

4. You can also use this method to make a puppy or other small animal you like and paste it on another paper cup.

5. Punch a small hole in the center of the bottom of the two paper cups (now turned into cartoon microphones).

6. Thread both ends of a long rope (the length must be more than 10 meters) into the small holes in the bottom of the cup, and then tie a big knot.

7. After the small phone is made, put one of the microphones of the small phone to your ear, and then ask your friend to hold the other microphone and stand 10 meters away from you (if the rope is If the length is more than 10 meters, then you need to stand farther away from you (that is, the length of the rope is the distance between the two) and sing or speak into the microphone. The rope should be pulled tight and should not come into contact with anything else.

8. Although you and your friend are 10 meters apart, you can still hear his voice clearly. Experimental principle: The sound of your friend singing or talking will cause the bottom of the paper cup (microphone) to vibrate. The vibration is transmitted along the rope to the paper cup next to your ear, causing vibration, and then causing the vibration of the air next to it. So, you Can hear your friend's voice clearly. (This is much clearer than if you were speaking directly from the same distance and at the same volume, because sound travels better in solids than in air.)

Obedient and disobedient eggs

1. Experimental materials: a few eggs, some sand, candles, markers or watercolor pens, and colored paper.

2. Take two eggs, poke a hole in the smaller end, empty the egg white and yolk inside and dry the empty egg shells in the sun.

3. Fill the empty eggshells with sand accounting for about 1/4 to 1/3 of the total volume.

4. Take out one of the eggshells filled with sand. You will be surprised by how obedient the egg is. The egg will stay in whatever position you put it in. Look, it can stand steadily on the mouth of the small medicine bottle like an acrobat. You can also balance it on various inclines, as long as the surface isn't too slippery. If the top opening is sealed, it can still stand upside down with its little head down. But in order for it to maintain your position, you'd better place it and tap it a few times to make the sand inside level.

5. Pick up another eggshell filled with sand, let it stand upright and gently tap it a few times to make the sand level. Light the candle and let the wax oil drip on the sand to fix the position of the sand. .

6. This makes a disobedient egg. No matter what position you put it in, it always returns to its original position. If you use colored paper to make a little hat for it and draw a cute face, it will become an interesting roly-poly. Experimental principle: The original center of gravity of the egg is in the middle, so it is difficult for you to make it "obedient" or "disobedient". After loading the sand, the center of gravity of the egg is on the sand.

Before the sand is fixed, as the position of the egg changes, the center of gravity of the egg, the sand, is always located at the lower part of the egg in this position. The egg is heavier at the bottom and lighter at the top, which maintains the balance of the position. When the sand is fixed to the lower part of the upright egg, it also becomes a tumbler due to the principle of the center of gravity.

Snake-shaped windmill on candle

1. Production materials: pins, empty film boxes, candles, thin plastic straws, pencils, cardboard, and scissors.

2. Draw a spiral line on the cardboard, and draw a snake's head shape at the end.

3. According to the figure, cut along the line and poke a small hole in the middle, which should just be able to pass through a thin plastic straw. This is the snake-shaped windmill.

4. Now start making the tripod. First, insert a pin into the eraser end of the pencil, then cut a small piece of thin plastic straw and seal one end, and put it on the pin to form a cap.

5. Make a round hole on the top of the empty film box and insert the pencil vertically.

6. Pass the small hole in the middle of the snake-shaped windmill through the cap, and the windmill is completed.

7. Light the candle under the windmill and you will see the snake start to rotate. The windmill will have the same effect if placed anywhere above a stove or heater. Why does this happen? Because warm air is lighter than cold air, rising warm air can turn the windmill. In daily life, in a room, the rising warm air keeps rising, flows along the ceiling to the window, is cooled at the window and then falls to the floor. When it is heated, it rises again... Gliders do not have engines, but they often have something called a thermal barrier (rising). Thermals) warm air rises, which causes the glider to rise.