One day, I read in a science book that sugar water can make invisible ink, so I started an experiment driven by curiosity.
I mixed the sugar water first, dipped my brush in sugar water, and wrote the word "open the door" on the paper. Then I dried the paper door. There's nothing. I began to doubt this book. Finally, I burned it with a lighter and saw a light brown word. When I saw it, I was ecstatic and immediately said to my mother-in-law who was watching TV: "Mother-in-law, come quickly, I will do magic for you!" " So, I took another piece of white paper, wrote the word "mother-in-law" on it, dried it with a hair dryer, and there was nothing left. I quickly asked my mother-in-law: "Do you believe it or not? I can write the word' mother-in-law' with fire without a pen. " Mother-in-law shook her head, obviously not believing it.
The lighter was baked for a while, but it was baked for a long time. I accidentally burned the paper. My mother-in-law smiled. I was a little anxious and said, "Don't be proud, wait a minute." I wrote those two words on a piece of white paper and dried them. This time I just baked them for a while, and the words appeared. I smiled proudly, and my mother-in-law quickly took the paper from me and read it over and over again, but I just didn't understand it.
Little friends, do you understand? If you don't understand, let me tell you something!
Because after writing words on paper with sugar water, glyphs and patterns will disappear after drying, and after baking, glyphs and patterns will appear light brown due to dehydration of sugar.
Use your head and think about what other liquids can be used as invisible ink besides sugar water.
Science is magical!
Last winter vacation, I went back to Lianyungang to play.
One night, I went to my sister's house to sleep, and I used to chat with her before going to bed. My sister told me that it snowed in Lianyungang some time ago! Snow is white, jumping in the air, like a lovely spirit. The next morning, the earth was white and covered with silver, but at noon, the snow began to melt. But when it snows, we feel colder than when it snows. ..... "Ah? ! "After listening to my sister, I was taken aback. "Why?" I got to the bottom of it again. My sister shrugged and said she didn't know. I thought to myself.
According to common sense, it is cold, and it snows below zero degrees Celsius. At that time, it must be very cold! When the snow melts, when the sun is warm, people should feel very warm! In contrast, needless to say, it is definitely much warmer when it snows than when it snows! But according to my sister ... impossible! Is my sister lying to me? Don't!
When I saw my parents the next morning, I spoke. It was a problem at night. These words can't wait to be said before I agree. Mom and Dad smiled and said, "You can check online."
I went back to my sister's house, turned on the computer and went to Baidu. Please log on to the website to check.
Suddenly, a line came into my eyes:
When water freezes, it releases heat, and when ice melts into water, it absorbs heat. But according to the basic law of thermodynamics, the heat of an object can only be transferred from a high-temperature object to a low-temperature object. The mutual conversion temperature between water and ice and snow is 0℃. When water freezes and releases heat to the environment, the ambient temperature will rise, but the maximum temperature cannot exceed 0℃, otherwise the flow direction of heat will "turn around"; On the other hand, when snow melts into water, it absorbs heat and lowers the ambient temperature. However, it is impossible for the minimum ambient temperature to drop below 0 degrees Celsius, otherwise the environment below 0 degrees Celsius will "reverse" the melting process of ice and snow. Therefore, in theory, snow can never be lower than the melting temperature. Comment: Many scientific inventions or discoveries are made inadvertently.
One day in the summer vacation, I was doing my homework at home and accidentally spilled ink from my pen on my notebook. I was busy reaching for the paper, trying to clean it, but I found that the paper in the wastebasket was almost used up, and there were only two or three sheets under it. When I took it, I had to reach down hard to get it. It is time-consuming and laborious, which is very inconvenient. I can't help thinking: Is there any way to solve this problem? I thought about it for a long time, but I didn't come up with any good ideas. Suddenly, the pedal trash can in the living room reminded me, yes! Just put a tray under the wastebasket, open the wastebasket, hold it up, close it and fall off. This will solve this problem!
Do it! I first found a box of about the same size, then cut off the lid of the box and processed it into two symmetrical halves like an old window, and put it aside for use. Then find a plastic wrap (plastic bags can also be used) and cut it into a rectangle as wide as the box, which is longer than the box 10- 15 cm. Then stick the two lids cut first on the box and fix them with adhesive tape, but not too tight, so that the lids can be opened easily. If it is too tight, it doesn't matter. You can stick two magnets on the lid of the box, and then stick two magnets at the same position on both sides of the box, and it's OK. Finally, aim both ends of the plastic wrap at both ends of the box and stick it. It should be noted that it is not necessary to stick all the plastic wrap on the lid, and both ends of the plastic wrap can be attached to the outermost end of the box.
In fact, this method can not only be used to hold toilet paper, but also some small ornaments, children's puzzles, craft paper, crayons, medicines and so on can be put in such boxes. Here, I would also like to remind you that because the plastic wrap is too thin, hard plastic bags should be used for items that are too heavy or pointed to prolong the service life.
This is the case with technology. As long as you are good at paying attention to your surroundings, there will be a steady stream of technological inventions flashing in your mind!
With the autumn wind, golden leaves fall in succession. I did cleaning work in front of the door and found an interesting phenomenon: most of the leaves on the ground are "facing the loess and facing the sky". Why?
Are other fallen leaves the same? I want to take another look. During this week, I went to observe the fallen leaves of many trees. As a result, I found that most of the fallen leaves are "facing the loess and facing the sky".
I think we should do a simulation experiment to verify my idea. So I made a kite that can fly like a leaf. I didn't fly the kite many times because I was not good at flying it. I remember when the kite landed, it always landed on the bamboo side. Is this the same as falling leaves?
Are the leaves as heavy as my kite? With this assumption, I took many different kinds of leaves for observation. I found that the veins on the leaf epidermis seem sparse and smooth, and the veins on the back of the leaf are closely arranged and rough. So with the help of my father, I made a model of the blade, woven into a net with some fine iron wires, some sparse and some tight. Then connect the sparse barbed wire and the dense barbed wire into the front and back sides. Then I threw the "blade" from the air 10 times, 8 times with the tight side of the barbed wire facing down, and 2 times with the sparse side of the barbed wire facing down.
Through the experiment, I was suddenly enlightened, so I went online and looked for information about leaves in books, and finally understood the scientific secret of fallen leaves "facing the loess and facing the sky" It turned out that two cell layers with different structures formed the "back" and "front" of the same leaf. Because of the different specific gravity, the leaves will turn over and change in the process of falling, with the heavy face facing down and the light face facing up, thus landing. Therefore, the tight side of the cell after landing is loess, and the cell coefficient is light.
Science is really interesting. I will do more such experiments in the future, and do more and more complicated experiments when I grow up to benefit mankind.
On Sunday, my mother and I did an experiment together.
I took a dry empty cup, a lighter, some candles and some limewater according to my mother's instructions.
First, mother took out a candle, lit it carefully and held it vertically. Wax oil dripped on the table. Mother put the candle on the table when the wax oil didn't solidify. Then, my mother shone an empty cup on it. At this time, the candle, like a clever child, put out Mars. I didn't think the experiment was so strange after reading it, but I couldn't say why, so I had to ask my mother.
Mom said that because the fire needs oxygen when it burns, and the cup covers it, the oxygen in it is limited, and soon the flame will burn it out. When there is no oxygen in the cup, it will go out automatically.
Next, my mother poured the clarified limewater into the beaker, then rinsed it off, and a layer of limewater was attached to the beaker wall. Put this beaker on the flame again, and the limewater on the beaker wall will be turbid in a moment.
"What is this?" I want to know.
Mom said with a smile, you'd better ask the computer teacher!
As soon as I heard this, I turned on the computer and looked it up. It turns out that this is because the candle burns and produces carbon dioxide. As soon as lime water comes into contact with carbon dioxide, it will undergo chemical changes and produce white solid calcium carbonate insoluble in water. "Oh, I see!" I hurried to call my mother and show her the instructions on the computer. Mom smiled and said, "You learned a new knowledge today."
What an interesting experiment! I will do more experiments and learn more scientific knowledge in the future!
This summer vacation, when our family went to Japan to play, it was strange to find that the Japanese actually drank tap water from the tap. Didn't you always say you can't drink raw water? Suddenly, a string of question marks came to my mind. So, I made a survey of tap water.
I. Classification of tap water (hard water and soft water)
One day, I looked at my mother curiously and asked, "Why can Japanese drink tap water directly from the tap?" "Because Japanese tap water is soft water, and most parts of China are hard water." Mother answered with a smile.
Second, hard water and soft water substances.
It is said that we all drink soft water and hard water is bad for our health, but why? It dawned on me after I checked the information. It turns out that hard water contains a lot of calcium and magnesium plasma. If we drink it, it will be harmful to our health and cause gastrointestinal dysfunction, which is called "acclimatization". But as long as the hard water is boiled, the calcium and magnesium plasma in the water will precipitate into scale and become soft water that we can drink. But there is little calcium and magnesium plasma in soft water, so we will be healthier after drinking it. I remember being naughty when I was a child and drinking a glass of raw water. As a result, my stomach ached for a long time. Drinking tap water in Japan is nothing at all, but drinking a lot!
Therefore, Japanese tap water has been purified from hard water into soft water, while China only purifies the water in rivers into hard water. I really hope that China can purify hard water into soft water like Japan, so it is much more convenient for us to drink water!
On Sunday, my mother and I did an experiment together.
I took a dry empty cup, a lighter, some candles and some limewater according to my mother's instructions.
First, mother took out a candle, lit it carefully and stood it upright. Wax oil dripped from the table. Mother put the candle on the table when the wax oil didn't solidify. Then, my mother shone an empty cup on it. At this time, the candle, like a clever child, put out Mars. I didn't think the experiment was so strange after reading it, but I couldn't say why, so I had to ask my mother.
Mom said that because the fire needs oxygen when it burns, and the cup covers it, the oxygen in it is limited, and soon the flame will burn it out. When there is no oxygen in the cup, it will go out automatically.
Then, my mother poured the clarified limewater into the beaker, washed it and dumped it, and a layer of limewater was attached to the beaker wall. Put this beaker on the flame again, and the limewater on the beaker wall will be turbid in a moment.
"What is this?" I want to know.
Mom smiled and said, you'd better ask the computer teacher!
As soon as I heard this, I turned on the computer and looked it up. It turns out that this is because the candle burns and produces carbon dioxide. As soon as lime water comes into contact with carbon dioxide, it will undergo chemical changes and produce white solid calcium carbonate insoluble in water. "Oh, I see!" I hurried to call my mother and show her the instructions on the computer. Mom smiled and said, "You learned a new knowledge today."
What an interesting experiment! I will do more experiments and learn more scientific knowledge in the future!
At the end of last year, just before the festival, my mother bought me a daffodil. I was so happy that I put it in the basin as my mother said, then poured clean water into it and put some pebbles in the basin.
I change the water once every three or four days. My mother said that the Spring Festival would be held and the flowers would be particularly fragrant. A few days later, daffodils sprouted, much like onion seedlings. About a month later, several buds grew out of the green leaves.
The Spring Festival is coming, and those buds haven't bloomed yet. It may not know how anxious I am to see the flowers! After the Spring Festival, not only did it not bloom, but the buds withered. Mother told me that it was dead and hopeless. I'm so sad! I am determined to find out the cause of its death. So, I went to the computer to find information. It turns out that the growth of daffodils needs sunlight, and the suitable temperature is 12℃-16℃. If the water temperature is too low, daffodils will only grow leaves and will not bloom, or even die. During that time, the south was hit by a once-in-a-century heavy snow, and the temperature in our place dropped to 0 degrees Celsius, which lasted for more than ten days. I didn't take any heat preservation measures to protect the flower buds, which led to the death of daffodils. I just froze to death because of my mistake, and I regret it.
I see, it takes knowledge to raise daffodils! Although daffodils don't need any flower fertilizer, they only need water. But in order to make daffodils grow strong, they should be taken to the balcony to bask in the sun during the day. If you want to postpone the flowering period, you can lower the water temperature, not too low, 10 degrees Celsius is appropriate. In addition, if you can't see the full flower buds before the festival 10, you can use water heating to promote the flowers, and the water temperature should be close to the body temperature. With this experience of failure, I believe that a fragrant "Ling Boxian" will be raised by the end of this year.
Last week, my mother bought me a small compass.
I turned the compass around and couldn't understand why its hands always pointed to the surface. In the evening, my father came back and saw me playing with a compass. He asked, "What's the matter?" I said, "Dad, why does the compass always point to the water?" Dad said, "The compass was invented by our ancestors. Our ancestors knew that magnets can absorb iron, so they made a compass that can move freely. " . Why can a compass point the way? It turns out that the earth is a very big magnet. Like a magnet, it has two poles, one is called geomagnetic North Pole and the other is called geomagnetic South Pole. Because the compass is a magnet, it can move, and the magnet is like-minded and opposites attract, so the compass on the earth always faces the geomagnetic north pole and the geomagnetic south pole. ""Oh, that's what it is. It's so interesting! " I said.
Dad also told me that the compass was one of the four great inventions in ancient China, and the earliest compass was called the compass. I asked my father, "So, how to use this compass?" Dad said, "put it flat, and then the pointer will rotate under the action of the geomagnetic field." When it stops, one end points to the south and the other end points to the north. " Compass is mainly used to tell the direction when the direction is unknown, but it can't be used in some places with unstable geomagnetic field, such as deserts and some canyons. "
Ships sailing on the sea and planes flying in the sky need compasses to point out the direction; When we travel to the suburbs, the compass will also bring us great help ... the compass is really our good helper!
Science Composition 10 There are many problems and mysteries hidden in the vast world, some of which are universal, while others are very strange. I have met some strange things.
I remember that day my mother bought a pot of flowers called mimosa from the flower and bird market. I saw that its branches are very thin. From a distance, the leaves are connected, but they are actually made up of many smaller leaves. I couldn't help reaching out and touching it, but when I touched it, its leaves closed tightly and then slowly opened. This is really fun! Playing, I can't help wondering, why does it have this reaction?
So I looked up the information about mimosa on the Internet. It turns out that there is an enlarged organ called "leaf pillow" at the base of its petiole. There are many parenchyma cells in the leaf pillow, which is very sensitive to external stimuli. Once it touches the leaves, the stimulation will be immediately transmitted to the occipital bone. At this time, the cytosol in parenchyma cells began to flow into the intercellular space, which reduced the expansion ability of cells, reduced the intercellular pressure in the lower occipital region, and the leaves closed and the petiole drooped. 1-2 minutes later, the cell fluid gradually flows back to the leaf pillow, so the leaves return to their original appearance. The above phenomenon of Mimosa leaves is a physiological phenomenon, and it is also the result of Mimosa adapting to the external environment for a long time in the process of system development. Because the mimosa originated in the tropical region, where there are many storms, when the storm blows the leaflets, it immediately closes the leaves to protect them from the storm, thus gradually forming this physiological phenomenon.
Searching the information of mimosa has also increased a lot of knowledge. There are so many magical places in a piece of grass. I wonder how many things in the world are still waiting for us to discover. This is of course the mystery of nature!
Scientific paper composition 1 1 Title:
Why do frogs croak in the rainy season?
Text:
One day this summer, after a heavy rain, I stayed at home and felt bored, so I went out for a walk by the lake. When I passed the lotus pond, I suddenly heard the cheerful cries of frogs from the pond, so I became interested and caught two and took them home.
Then, I took a big vat, filled it with water, put a piece of plastic foam, put two frogs on the foam, and squatted on the ground to observe. But something unexpected happened, and then it rained continuously. The silent frog just cried more and more happily, as if he had been expecting rain. At this moment, they "sang" and "danced" happily. At this moment, I wonder if rainy days are good for them. So I started the second experiment.
It rained again the next day. This time, I looked at them in the rain with an umbrella. I saw many pests break out of their shells and fly around frogs, which became frog food in vain, hehe! No wonder frogs are so happy. I have done five or six experiments in a row, and the result is still the same. However, to be on the safe side, I checked the encyclopedia and finally found the answer in the book: it turns out that frogs breathe not only by lungs, but also by bare skin. On rainy days, the air is full of water, which is beneficial for frogs to breathe through their skin. Moreover, small insects breed very quickly in rainy days, which is also a good time for frogs to catch. Therefore, frogs croak happily in rainy days.
Through this experiment, I not only discovered many secrets of frogs, but also understood a truth: no matter what happens, I can't hear from hearsay, and that answer is inaccurate. But do it yourself, and make a conclusion after careful observation and analysis. This is our goal.
Conclusion:
Frogs can breathe through their skin in rainy days, which is also a good time to catch pests. So when it rains, frogs will cry happily.
Last week, my mother bought me a small and exquisite compass.
I turned the compass around and couldn't understand why its pointer always pointed south. In the evening, my father came back and saw me playing with a compass. He asked, "What's the matter?" I said, "Dad, why does the compass always point south?" Dad said, "The compass was invented by our ancestors. Our ancestors knew that magnets can absorb iron, so they made a compass that can move freely. " . Why can a compass point the way? It turns out that the earth is a very big magnet. Like a magnet, it has two poles, one is called geomagnetic North Pole and the other is called geomagnetic South Pole. Because the compass is a magnet, it can move, and the magnet is like-minded and opposites attract, so the compass on the earth always faces the geomagnetic north pole and the geomagnetic south pole. ""Oh, that's what it is. It's so interesting! " I said.
Dad also told me that the compass was one of the four great inventions in ancient China, and the earliest compass was called the compass. I asked my father, "So, how to use this compass?" Dad said, "put it flat, and then the pointer will rotate under the action of the geomagnetic field." When it stops, one end points to the south and the other end points to the north. " Compass is mainly used to tell the direction when the direction is unknown, but it can't be used in some places with unstable geomagnetic field, such as deserts and some canyons. "
Ships sailing on the sea and planes flying in the sky need compasses to point out the direction; When we travel to the suburbs, the compass will also bring us great help ... the compass is really our good helper!
Fourth grade: Chen
Science composition 13 "goo goo ……" I was doing my homework when I suddenly heard a strange cry from the kitchen. Born timid, I couldn't help but get a fright. I crept over to have a look, but I didn't find anything suspicious. At this time, there was the sound of "goo goo" again, and I didn't notice that it was the pickle jar at the foot. Gee, how can the pickle jar bubble? Could it be that air went in and then came out of the water? However, the lid of the pickle jar is tightly covered.
Not a breath of air can run in!
My sister came back from work before she entered the gate. I couldn't wait to run up and ask, "Sister, sister, why are there bubbles in the pickle jar?" My sister said with a smile, "If the vegetables in the pickle jar are soaked for a long time, they will produce an anaerobic bacteria, which can multiply in large quantities without oxygen." When fermenting, gas will be released, so bubbles will appear in the pickle jar. "
What? Anaerobic bacteria? I am most afraid of bacteria. They are all bad things. How do they appear in food? What should I do if I get sick after eating these things? My sister's answer can't satisfy my curiosity. I brought an encyclopedia to find the answer. Ah, the answer is here! It turns out that some bacteria (such as yeast and anaerobic bacteria) exist in nature, which can cause food fermentation, produce acid and release gas at the same time. They are harmless to human beings. I think: In the past, the steamed bread made by my grandmother was only the size of a fist. After steaming, it became the size of a palm, fragrant and sweet. Thanks to yeast! I didn't expect fungi, which I hated in the past, to play such an important role in our lives.
Just when I was about to get carried away, a big bubble suddenly appeared in the pickle jar. My sister said to me, "In fact, there are many wonderful phenomena in nature. As long as you pay attention to them, you will find them. " Look, that pickle jar called "Goo Goo" is a good proof.
Science Composition 14 We learned Tin Pots and Pots, knowing that tin pots rot easily in the soil, and a small question mark popped up in our mind: So where does iron rust fastest? To this end, I made a small experiment after repeated thinking and research.
I prepared three small pieces of iron in advance. One is placed in a place with low temperature-refrigerator; One is buried in the soil; The last one was put in salt water. Let's see which will make the tin rust faster. At the end of the day. Before I came to the refrigerator, I carefully took out the iron sheet and observed it carefully. The iron sheet hasn't changed at all. I then went to the flowerpot and dug out the iron pieces hidden in the soil, and the result was still the same. Finally, I came to the cup and took out the iron piece soaked in water, but there was no change at all. This annoys me: "Will it take a long time to have an effect?" I left the experimental site with questions. A few days later, I went there again and was surprised to find that the iron sheet in the soil was a little rusty, while the iron sheet in the salt water had rusted. What the hell is going on here? With this question, I turned on the computer and realized that it was the reaction of the primary battery, and the ions were conductive. Because two metals usually have different activities. Take iron and copper for example. Because there is moisture in the air, water usually contains acidic gases, such as carbon dioxide. When the iron sheet encounters acid, it loses electrons and becomes iron ions, while the electrons move to copper through the metal and then are reduced to hydrogen to form primary electrons. This reaction is called hydrogen evolution reaction. This corrosion of iron is called electrochemical corrosion, and the electrochemical corrosion rate is faster than that of general oxygen reduction corrosion.
Experiments and data prove that salt water will make iron rust faster!
Science composition 15 be familiar with the word science and technology. Simply put, technology is technology. In a broad sense, it refers to the sum of natural science and technology and social science and technology.
Since the reform and opening up, with the passage of time, science and technology have mushroomed in the motherland. Looking around life, technology is everywhere, and technology is by my side!
Walking on the road at night, there are electric lights to illuminate us; Call a friend and take out your mobile phone at your fingertips; Back home, turn on the TV to watch the news, turn on the computer and chat with friends; Mother steamed rice with a rice cooker; Turn on the electric heater; The whole family is sitting around, enjoying the delicious food prepared by my mother with an electric wok ... Do you think we can leave technology anytime and anywhere?
Technology is very useful! For example, if there is no electric car, it will be inconvenient for us to communicate with distant relatives and friends; If there is no EMU, it will be difficult for people to travel everywhere. Without the space shuttle, it would be empty talk for people to go into space; If there were no icebreakers, it would be difficult for us to go to Antarctica. Without space instruments, it would be just an illusion for humans to land on the moon. ...
On the contrary, with technology, our life will be better-with fax, our documents can be easily sent out in an instant! With robots, you can be in a space that people can't reach; Using laser, you can make fitness equipment; With air conditioning, people can feel as comfortable as spring even in hot summer. ...
It is not difficult to see: all this, people enjoy the achievements of science and technology!
This shows that technology has helped us create a superior living environment; Science and technology have improved our quality of life; Technology is the crystallization of the wisdom of people all over the world!
We are engaged in technology, and we should constantly learn new technologies!
Science and technology are around us, and we must vigorously develop science and technology!