The composition of the third season open class.

Five essays in the third quarter open class.

The open science course (the third season) will be officially broadcast on Tuesdays, Thursdays and Saturdays (except New Year's Eve to the sixth day) from 2023. 1. The following are five essays I brought to you about the third season open class for your reference!

The composition of the third science class (1 article) not only endows us with rich knowledge, but also enables us to understand many scientific mysteries in interesting experiments.

In science class, what we like best is doing experiments in the laboratory. In the process of doing experiments, we learn while playing, remember that knowledge faster and broaden our horizons.

Since the beginning of school, we have unconsciously accumulated a lot of knowledge in our minds. In the first unit of the science book Tiny World, we saw a strange world that we had never known before under the microscope. Microscope can help us to see cells and many tiny creatures, which is attributed to Levin Hooke, who created the microscope and made mankind take a big step forward in this respect. Under the microscope, we see chloroplasts, which are cells in the epidermis of plants. We also observed the epidermis structure of onion, which is composed of pieces of regular patterns and some small black spots. Those little black dots are nuclei. These little experiments stunned us!

Later, in the second unit of material change, we did an experiment about "pulling white sugar". The experimental materials are very common, just need some sugar, an iron spoon, a candle and a box of matches. After reading these materials, you probably already know what we are going to do! Yes, we are going to heat the sugar with a spoon. However, it should be noted that sugar only needs to be put into 1/3 of the spoon volume, and it should be placed at the top of the spoon to avoid scalding. Don't think this is a very common experiment, because the change of sugar below has gradually turned everyone's mouth into an "O" shape. The color of sugar changes from white to yellow, then gradually to brown, and finally to black. This is caramel. When sugar burns, it begins to bubble gradually. The reason for smoking is that the spoon burned out the carbon! When the sugar begins to bubble, it can almost be taken out of the fire. After taking it away for a while, you will be surprised to find that the sugar has solidified into a solid! Before doing this experiment, we watched the video of "pulling sugar". After reading it, we all know what to do! Just boil the sugar in water, add a proper amount of citric acid when it is golden yellow, and then cook it. After cooking, you will start to pull sugar like Lamian Noodles!

Under the guidance of science, we understand the truth that "the world is full of wonders". Our little heart can hardly bear the temptation and surprise brought by scientific experiments! Science will never stop, and there are still many mysteries in the world to be discovered and created. Science is a big world, in which we can get incomparable gifts!

Science can tell us a lot of knowledge. If you want to understand the mystery, you need to do the experiment yourself or ask for help from _.

Well, I finished my homework early and watched a movie about spies with my father. The sudden appearance aroused my curiosity. In the movie, a spy holds a cotton swab in his hand, then squeezes out a plate of lemon juice with lemon, then dips the cotton swab in the lemon juice and writes on the paper. I guess the words on the paper must be information. However, when the paper dries, the words disappear with it. Then there is the actor who receives the information. He took the information and slowly burned it on the paper with a lighter. Soon, the words on the paper were displayed again. I pointed to the scene on TV and inexplicably asked my father, "Dad, what's the matter? Why did the word disappear? "

Dad shook his head and said, "I don't know that either."

"However, you can do an experiment exactly like him yourself, and maybe you will know the secret."

"Well, it doesn't matter." I listened to my father's words and began to prepare materials.

After a while, the materials were ready: a bowl of lemon juice, a cotton swab, a clean white paper and a lighter.

I learned from the spy on TV. I wrote a lot of words on the paper with a cotton swab dipped in lemon juice and put it on the table to dry. After about a minute or two, the conversation dried up. I took out my lighter and lit it under the paper. After a while, the words that disappeared on the paper can really be seen again. I shouted, "OMG, that's amazing!" " "

But why is this? I was puzzled and finally decided to ask "Baidu".

This is what Baidu told me: the starch contained in the paper will react with iodine to form iodine starch molecules, which are dark blue and purple; Lemon juice is rich in vitamin C, which will be colorless when it reacts with iodine. So the part where you write or draw with lemon juice will not change color.

Because lemon juice contains an ingredient called cellophane, writing on paper can reduce the ignition point of paper. As long as it is baked with fire, the writing part of lemon juice will be burnt first and yellow words will appear.

This reminds me of another movie: a little spy sells eggs in the street every day, and the people who buy eggs are always those. I found that there was information in the egg, because the spy wrote on the eggshell with a pen dipped in vinegar, but when the egg was cooked, the words would be on the surface of the protein, so the information would not be found.

Through these two examples, I fell in love with science even more, and I like science even more. It also made me understand that I can find a lot of scientific knowledge in nature and life.

Knowledge is the ladder of human progress, so the sign of our growth and progress is to learn knowledge and make our cultural heritage deeper.

On, our school held a "popular science caravan" visit experience activity. In the science and technology activity room of the school, those interesting popular science knowledge aroused my strong curiosity.

We saw all kinds of scientific and technological exhibits, which was really dazzling. The most unforgettable thing is Huarong Road. Huarong Road is an ancient game in China. With its changeable and tireless characteristics, it, together with Rubik's Cube and Independent Diamond Chess, is called "the Three Superman in Intelligence Games" by foreign intelligence experts.

This exhibition mainly consists of a booth, a long slot, a chessboard and ten thin sliders of different sizes. We need to use the gap on the chessboard to move the slider so that Cao Cao can exit from the opening in as few steps as possible ... We still haven't succeeded, and it seems that our hands-on ability needs to be improved.

There is also an activity called "Sound Wave Visible", which requires us to pluck the strings with our fingers, then turn the drum and observe the vibration track of the strings. In this experiment, a black and white striped background drum is used to "freeze" the fluctuation of the sounding guitar strings, thus showing the fluctuation form of the strings that were not easy to be observed by the naked eye. Through experiments, we know a scientific principle: sound propagates in a fluctuating way, the amplitude is expressed by the volume, and the frequency is expressed by the tone of the sound.

What scares me most is the "gentle electric shock". This experiment must be done by two people together, so I put my hand in contact with the metal handprint, and my friend pressed the start button to let me feel the electric shock. We still have a question, electricity is terrible, so how much current is harmful to human body?

The teacher told us that the safe current of human body is 30 mA AC and 50 mA DC. Although the voltage generated by the hand-cranked generator here reaches 1000 volts, the current is strictly limited below 15 A ... and the current generated by itself is very small, which will not cause harm to human body. After listening to the teacher's explanation, we suddenly realized!

"Six-star puzzle", I am very interested in the topic as soon as I see it! Fill in the numbers from 1 to 12, so that the sum of four numbers in each row is 26, which is a difficult problem! We thought it over carefully, but we always got it wrong. We lost the whole set and had no choice but to ask the teacher for help.

"The cone rolls up", this experiment consists of a double cone and an inclined track. When the cone is placed at the lower end of the track, it will be surprised to find that the cone actually rolls along the track. What is the secret of this? It turns out that the cone rolling is only a superficial phenomenon, but in fact its center changes from high to low in the process of cone rolling. The two sides of the inclined rail are arranged in a figure of eight, with one end low and one end high. The distance between low-end tracks is small, the fulcrum is close to the center of the cone, and the center of gravity of the cone is high, while the distance between high-end tracks is large, and the fulcrum is close to the outer edge of the cone, and the center of gravity of the cone is low. So when the cone is placed at the lower end of the track, it will roll up along the track, which is the mystery of the cone rolling up. Under the action of gravity, the object will always move according to the law of lowering the center of gravity for stability.

Wow! This world is really amazing. I want to study hard, master more scientific knowledge, ask questions boldly, explore bravely, understand the world and change it!

Comments on the third season open science class (Part IV) "Science" is a very profound thing. It is like an ocean countless times larger than the universe, and we are like one of thousands of creatures in the ocean. We explore every day and find that this is more conducive to our human knowledge, especially those pioneers in the field of knowledge-scientists. It is constantly updating our environment, so that we can have a better life.

In 2 1 century, science will become human life. If you don't know science, you can't survive in this society. If you have a scientific seed and cultivate it carefully, it will take root and sprout with time and bear countless fruits. The "Nobel Prize" is to reward those scientists who use their wisdom and hard work to cultivate fruitful results for the benefit of mankind, so that they can become our pride and become an example for us to learn. At the same time, encourage them to make more outstanding contributions to us and even to all mankind. 466 scientists from more than 20 countries won the Nobel Prize. When they walk to the podium of the Nobel Prize, they represent that they have great wealth created by science. It also represents their contribution to mankind. We should cheer for these people and cheer for them to change the world with science.

The power of science is infinite, and it will bring you unexpected wealth. Therefore, we should love science from childhood, but if we don't dig deep into the mystery of science and practice it, we will never get the happiness of science. Some people only know one thing and don't know another. How can they succeed if they only understand the surface and don't explore deeply? So be brave in trying and innovating. Used to overthrow the previous words and conclusions. And what you end up with is your own results.

How far is the Nobel Prize in Science from us? Needless to say, as long as you sow the seeds of science from an early age and study hard, it will be around us.

Some people think that science is difficult to understand, while others think that science is too abstruse to explore. In fact, science is everywhere around us, no matter how big or small, it can be solved by scientific methods.

Let me talk about chopping wood. Perhaps many people think that chopping wood is a simple matter. Just pick up an axe and chop it hard. Actually, it is not.

One day, my father bought a big bundle of firewood, smiled at me and said, "Sister Yu, let's have a competition today to see who has the greatest skill, shall we?" Of course I won't bow my head and admit defeat. Isn't that chopping wood? Don't trust me. I can't

The game started, only to see my father break up easily. I also split it with all my strength. At this time, I found that my father's chopping wood was so light, and I thought, "Hum, my father must have kept his sharp axe for himself." I said quietly to my father, "father, let's change an axe." I like yours. " My father switched with me without saying anything. My axe is like a duck to water in my father's hand, and I have done better. Before long, my father's share was completed. Look at me, my hands are blistered, I'm so tired that I'm sweating all over, and my task is still early.

I must admit defeat, but I must lose clearly. I asked my father, "What is this?" Father said: "If you don't chop along the grain of wood, you will waste a lot of energy. If you use scientific methods, it will be very labor-saving." Also, if firewood is long, it should be cut, not flat on the ground, but on the top of your head, which will cut it. "I chopped wood according to my father's method, and it was finished in a short time. The scientific method is really useful, so I have to give up.

Although I lost, I am glad that I have gained another life experience, and science is around us.