The composition of the fourth grade experiment is 1 "Hey? What happened to the handkerchief? It didn't burn. It's amazing! " There are many questions in the classroom, alas! Know what we're doing? Ha ha! We are doing experiments!
In the composition class in the afternoon, Miss Wang brought a bottle of wine, a handkerchief, a piece of paper, a lighter and a book. "Miss Wang, what are you doing?" The students said to themselves. A naughty child said, "Miss Wang may have set the house on fire! Let's run, haha! I don't want to make roast whole sheep! "
Seeing that we are young and curious, Miss Wang told us, "Today we are going to do an experiment." But the students began to talk again. "What experiment is the teacher going to do?" "Look, everyone, what is this?" The teacher took out a handkerchief. "Is it not a soft handkerchief? What's the big deal? " "This is no ordinary handkerchief! This is a handkerchief that won't burn! " "A handkerchief that won't burn? No way! Teacher, you are kidding us! " We talk endlessly and don't believe it.
Before we finished, Mr. Wang poured wine into the cup. "ah! Hey! Miss Wang, you should drink this drink! Do you need to change some hot water in such a cold day? " We couldn't help crying. After a while, there was a strong smell of wine everywhere in the classroom. Then, Mr. Wang put the handkerchief in the cup, tore off a piece of paper, lit it with a lighter and put it in the cup. In the blink of an eye, the red and blue flames quickly jumped out of the cup. As soon as we saw it, our mouth opened into a "χ" shape, only to see the teacher unhurriedly pick up the book and cover it on the cup. We are afraid that the teacher's books will be burned. Strangely, the fire went out after the teacher took the book down. After doing this for three times, our curiosity is even greater.
"Is the handkerchief safe now? Why won't books be burned? Why is the fire red and blue? Why did the fire go out? Why are these? " We explored the mystery with great curiosity.
The teacher told us: "the book won't burn because the ignition point is low." When the fire burns, it needs oxygen. When I cover it, it goes out. The flame is blue and white, because it is the flame of alcohol burning. Does everyone understand? "
"I see!" We answered loudly and confidently. It turns out that the flame of alcohol will turn blue, but the teacher hasn't told us what happened to the handkerchief. Just then, the teacher took it out with a pen.
"Look, everyone, this is the handkerchief." "wow! No way! It's incredible that the handkerchief is intact! " We are even more puzzled.
The teacher explained to us, "In fact, this is just an ordinary handkerchief. The reason why it won't burn is not because of the magic of the handkerchief, but because the burning flame burns alcohol, so the handkerchief won't burn out. " It suddenly dawned on all of us.
Through this experiment, I not only understand a lot of scientific knowledge, but also understand that there are many scientific truths and knowledge waiting for us to discover on the road of life. As long as you carefully observe and be good at thinking, you will definitely gain a lot!
Nature is a treasure house of knowledge. As long as you are willing to explore and think seriously, you can always get a lot of inspiration from it.
As soon as I walked into the classroom today, I saw an insulated water cup and a plastic water cup and thought, what are you doing today? The teacher came and solved the mystery in our hearts. The teacher said, "Let's do a little experiment today." We all craned our necks to see what tricks the teacher would play. The teacher first wrote two words "lose weight" on the blackboard and asked the fattest classmate in the class: "Do you want to lose weight?" Xiao Pang said he wanted to go. I thought, what does this have to do with the experiment?
After a while, the teacher said that whether you believe it or not, this bottle can make him lose weight without external help. Some people are dubious, some people don't believe it, and some people believe what the teacher said. The experiment has begun! The teacher carefully poured the hot water from the thermos into the plastic bottle first, and only heard the sound of running water, which soon filled it up and hot air came out from time to time. Then the teacher poured hot water back into the thermos, and a miracle happened! The bottle slowly became a slim girl like a big fat girl. Just as everyone was wondering, the teacher explained the principle to everyone one by one. The teacher said, "The hot water heats the air in the bottle, which makes the air volume expand. When the hot water is poured out from the heat source, the air temperature drops and the volume becomes smaller. If the bottle cap cannot be tightened to replenish the air, the plastic bottle will collapse."
There is so much learning in life! As long as we carefully observe and explore, there will be more discoveries!
In summer, you can often see a four-legged snake with scales like snakes on the roadside and in the grass. It is said that this four-legged snake is poisonous. If bitten by it, the skin will be red and swollen, and then rot. Is the four-legged snake really poisonous? In order to find the answer, our interest group conducted a study.
First, we caught a four-legged snake, anesthetized it and fixed it on the anatomical plate. Then use a disposable syringe to suck 0 in its mouth. 5ml of saliva, pour into a beaker and add 3ml of water to mix saliva and water evenly. Then put a little frog in it. An hour later, the frog was safe and sound. Is the time too short? Let it stay for one night. As a result, the next morning, we found that the little frog was still alive and swimming freely in the water, which was quite comfortable. Is the concentration too low? In order to make our experiment accurate and reliable, we caught four four-legged snakes in the wild and conducted the experiment in the same way as yesterday. As a result, the frog is still alive. From this point of view, the four-legged snake has no toxic effect on the little frog.
So does the four-legged snake have any effect on other animals? We caught a cat and set it free. Wipe 9ml of saliva on the cat to see if there is anything unusual. As a result, two days later, we found the cat unharmed. At this point, we began to relax people's dangerous words about the four-legged snake, and further increased our determination and confidence in the toxicity study of the four-legged snake. We decided to do experiments on ourselves to see if a four-legged snake has any effect on people.
We drew 0 from the mouth of a four-legged snake. 5ml of saliva on yourself. At first, my skin felt a little cold, but after a while, I felt nothing and had no adverse reactions. After half an hour, the skin is still unresponsive. This shows that the four-legged snake has no toxic effect on our human skin.
Through the above experiments and research, we understand that quadruped snakes are harmless to human beings. After consulting Dr. Xiao's knowledge base, we also know that quadruped snakes are actually lizards and skinks. They are mainly distributed in Guangdong, Zhejiang and other places in China, and mainly eat mosquitoes, flies, mantis and other pests. They are good friends of human beings and we should protect them.
Fourth grade experimental composition 4 In today's composition class, the teacher said, "Today we will do an experiment."
As soon as the voice fell, the teacher turned on the computer and several words appeared on the screen: How many times can a piece of paper be folded in half?
The classroom suddenly exploded, and some students shouted, "It's that simple?" Some students said, "At least you can get a discount of 10." Some students shouted, "Haha, I can fold it a hundred times."
The teacher calmed everyone down and said to us, "In this case, please finish the experiment."
Bring me the paper. I can't wait to fold it in half. The first two times were simple, the third time gradually hardened, the fourth time the paper began to swell, and the fifth time the whole paper almost turned into iron ... things became more and more difficult. When I finished folding for the sixth time and planned to fold for the seventh time, I found that I couldn't fold it no matter how hard I tried.
Then the teacher spoke: "Please raise your hand if you have folded it ten times." No one in the class raised their hands, and the teacher smiled: "Who said that folding 100 times was not a problem just now?" Then he said, "How many times did you fold it?" We said in unison, "Six times." Then we all laughed.
This is really an interesting experiment, and it also makes me understand that if you haven't done it yet, don't jump to conclusions.
Teacher's comment: according to the order before and after the experiment, the experimental activities are described clearly, and the rich details make the composition wonderful!