How to say gas pressure can make students understand it better?

Give you three teaching designs of gas pressure, and see if they can help you (pictures and tables can't be pasted, please forgive me! )

Teaching design of atmospheric pressure

First, the teaching objectives

(a) knowledge and skills objectives

1. Understand the existence of atmospheric pressure. Know that the atmospheric pressure is very large.

2. Understand the principle of Torricelli experiment.

3. Cultivate students' abilities of observation, analysis and induction.

4. Cultivate students' hands-on experimental ability.

5. Cultivate the ability to apply what you have learned to solve practical problems.

(2) Process and method

1. Analyze the principle of Torricelli's experiment to make students master the method of reasoning.

2. Infiltrate the idea of equivalence.

(3) Emotion, attitude and values

Through the study of the hemispheric experiment in Madeborg, let students love science. In the study of Torricelli's experimental principles, students can experience the fruits of rational thinking.

Second, the class schedule

1 class hour

Third, prepare teaching AIDS and learning tools.

(1) List of desktop experimental equipment: straws, gas containers, cored alcohol lamps, tweezers, iron shelves, quail eggs, sinks, large and small test tubes, thermos cups (filled with hot water), paper cups, sewing needles, cardboard, plastic suction cups and balloons.

(2) A set of multimedia courseware, a bottle of canned food, a gas container, a pitted alcohol lamp, a pair of tweezers, an iron shelf, a quail egg, a sink, a large and small test tube, a thermos bottle, a small amount of colored water, and a set of Madeburg experimental device.

Fourth, the teaching process

(1) Introduction to the new lesson: Students, today Mr. Luo is going to be a magician and perform two magic tricks for everyone. Here are two test tubes with almost the same inner diameter. Do you think they will fall if you don't hold them with your hands after they are overlapped and inverted? Pour more than half of the water into the big test tube, and slowly insert the small test tube into the big test tube. At this time, turn the two pipes upside down at the same time. Attention, something strange has happened. (Please answer: the small test tube not only does not fall down, but also rises. ) One more: I have a quail egg on my desk. Everybody, be careful. Now I'm going to let the small flask swallow the whole egg. Look at me. Look, I'm in! Did the teacher just enchant two little tricks? No, after learning the section "Atmospheric Pressure", the students will know why.

(2) Teaching a new lesson: Students recall the reason of liquid pressure in the previous chapter: liquid is influenced by gravity and has fluidity, so it has pressure on the objects immersed in it. Similarly, air is affected by gravity and has fluidity, so it also has pressure on objects immersed in it. This pressure is called atmospheric pressure, or simply atmospheric pressure. Some students may say that air is invisible and intangible, but I can know its existence through the wind formed by air flow. How do you know if there is such atmospheric pressure? The big screen demonstrated the experimental process of the hemisphere in Madburg, introduced the structure of the hemisphere, and then asked the students to draw air and then pull the hemisphere. Atmospheric pressure is always around us, and whether it is pumped or not, the outside of the hemisphere is always affected by atmospheric pressure. But before pumping, the internal and external air pressure values are the same, so it can't be displayed; After pumping, the external atmospheric pressure is much greater than that in the bottle, which shows that the two hemispheres are tightly pressed together. The experiment in the Madeborg hemisphere can strongly prove the existence of atmospheric pressure. In fact, there are many experiments to prove the existence of atmospheric pressure. Let's do some experiments with the equipment given to you on the desktop. Remember, atmospheric pressure can only be shown when there is a pressure difference between inside and outside. Look for it. How many experiments related to atmospheric pressure can you design? Group members can discuss and cooperate with each other to see which group thinks the most. Complete a record one by one. The form is on the table, too. Here we go. After a few minutes, ask the students to read the experimental records and analyze the reasons for the success or failure of the experiment. )

Through the experiment just now, the students found that some groups filled small test tubes with water and poured them out of the sink without sprinkling a drop of water, while others did the same experiment with large test tubes. Does this mean that atmospheric pressure can support water column at any height indefinitely? As early as 1640, the Archduke of Tuscany built a very beautiful fountain in his garden in Florence, northern Italy. In order to ensure adequate water supply, he dug a well in the garden, the wellhead was more than ten meters from the ground, and a high-powered water pump was installed. Dagong and designers think that the fountains and gardens in the morning must be beautiful. After the project was completed, the Grand Duke chose an auspicious day and invited relatives and friends to officially unveil the fountain. But it is very disappointing. Although the pump has been working, the fountain can't spray a drop of water. In fact, in the production practice at that time, such problems appeared more than once. Miners have long discovered that no matter how hard they try, it is impossible to suck the water in the mine to the ground 10 meters above. Although the fountain storm has passed, the problem is still left to scientists. How high a water column can atmospheric pressure support? What is the atmospheric pressure? Three years later, a young scholar found the answer. He is a student of Galileo Torricelli.

Because mercury is poisonous, we don't do Torricelli experiment in class now. Torricelli died at the age of 39 four years after the experiment. He was also a great scientist who devoted himself to science. In this experiment, we can understand the whole process through video recording.

Through experiments, we know that atmospheric pressure can support a mercury column of 76 cm, and the density of mercury is 13.6 times that of water. That is to say, the height that can support the water column should be 13.6×0.76m, which is about 10m m. If it exceeds this value, the power of the pump is useless. Moreover, if you violate science, you must choose an auspicious day.

Ask your classmates another question: Will there be atmospheric pressure around our human body? Yes, then why don't you crush us? All the students have seen movies and TV plays. When astronauts roam in space, they must wear thick spacesuits. Do you know why? What will happen without it? Students use their brains again to see what other phenomena around us are related to atmospheric pressure. Lenovo: the process of syringe absorbing medicine, pen absorbing water and plastic clothes hook hanging schoolbag.

Let's review together. Today, I mainly know the existence of atmospheric pressure and the size of atmospheric pressure. Going back to the two small experiments I showed my classmates at the beginning, can the students explain why? Students think again, is there any way to spit out the eggs completely? Inspire the students to operate the demonstration on stage and tell them that although atmospheric pressure can be abbreviated as atmospheric pressure, there is still a difference between atmospheric pressure and atmospheric pressure. Strictly speaking, atmospheric pressure is only a kind of atmospheric pressure, which is the pressure generated by the outside air; Air pressure also includes pressure generated by enclosed air, pressure generated by steam or other gases, etc. When the air pressure in the bottle is greater than the external atmospheric pressure, quail eggs are squeezed out.

Attachment: experimental record table for exploring the existence of atmospheric pressure

An example of atmospheric pressure teaching plan

Learning objectives:

1, to understand the phenomenon caused by the objective existence of atmospheric pressure.

2, understand the method of measuring atmospheric pressure, understand the size and unit of atmospheric pressure.

3. Understand the working principle of the pump.

4. Understand the phenomenon of using air pressure in life.

Learning process:

First, import:

★ Demonstration Experiment 1: For example, P92- Figure13.3-1C. Think about what force crushed the plastic can?

Second, the existence of atmospheric pressure.

1, thinking: P82 thinking and discussion.

2. Inquiry experiment: put a balloon in a vacuum glass cover, put a plastic ball with a hole outside the balloon, extract the gas from the cover, and observe the change of the balloon shape.

Conclusion: This experiment shows that the atmosphere has _ _ _ _ _ on the surrounding environment.

3. Give examples of atmospheric pressure in life.

Third, the measurement of atmospheric pressure.

1 ★ Inquiry Experiment 2: P83 Think about it and do it.

2. Watch the video.

3. 1 standard atmospheric pressure = pressure generated by mercury column = _ _ _ _ _ PA

4. Measurement of atmospheric pressure: types of barometers: _ _ _ _ _ _ and _ _ _ _ _ _.

5. Changes in atmospheric pressure:

▲ The size of atmospheric pressure is related to _ _ _ _ _, and also related to _ _ _ _. Atmospheric pressure increases with altitude and _ _ _ _. According to this principle, an altimeter can be made with a barometer. Is this altimeter accurate? What are the main factors that affect its accuracy?

▲ ☆ ☆ ☆ ☆ ☆ ☆ ☆ ☆ ☆ ☆ ☆ ☆ ☆ ☆ ☆ ☆ ☆ ☆ ☆ ☆ Try it and discuss it.

Exercise:

1, the following phenomenon, can't explain the existence of atmospheric pressure is ().

A, plug the small hole in the tea cover, so that the water in the teapot is not easy to pour out.

B, straws can suck drinks into your mouth.

C. When producing light bulbs, the air extractor can extract air from the bulbs.

D, two pieces of glass put together, there is water in the middle, it is difficult to separate.

2. As shown in figure A on the right, fill the cup with water, close the lid of the cup with a piece of paper, hold down the paper and turn the cup upside down. After letting go, the paper will not fall off, indicating that the paper has received an upward _ _ _ _ _ _ _ _. Put the cup in the position shown in Figure B, and the paper will not fall off. Figures A and B can show that the atmosphere has _ _ _ _ _ in all directions.

3, the following does not belong to the atmospheric pressure application phenomenon is ()

A. plastic clothes hooks can be hung on the wall to hang clothes.

B.a piece of paper can be filled with a glass of water without spilling it.

C. drink in a bottle that is opened with a straw.

D. liquid medicine can be injected into muscles with a syringe.

4. When using a syringe to suck liquid medicine, first push the piston into the bottom of the syringe, and then insert the needle into the liquid medicine. When the piston is lifted, the liquid medicine will flow into the syringe. The reason for this is ()

A. Make the air pressure in the syringe greater than atmospheric pressure, and the liquid medicine will automatically flow into the syringe.

B, making the air pressure in the syringe less than the atmospheric pressure, and using the atmospheric pressure to press the medicine into the syringe.

C, make the air pressure in the syringe equal to atmospheric pressure, so that the pressure of the liquid medicine is balanced and easy to flow into the syringe.

D the syringe itself has the ability to absorb liquid medicine.

5, about Torricelli experiment, the following statement is correct ().

The greater the inner diameter of the glass tube, the smaller the height difference between the inside and outside of the tube.

B. Pour more mercury into the mercury tank, and the height difference between the inside and outside of the tube will increase.

C. When the glass tube is tilted, the height difference of mercury level inside and outside the tube remains unchanged.

D. Part of the air enters the top of the glass tube, and the height difference of mercury level inside and outside the tube remains unchanged.

6, as shown on the right, in the Torricelli experiment of measuring atmospheric pressure, if the glass tube is tilted from position A to position B, the following statement is correct ().

A the length of the mercury column in the glass tube remains unchanged.

The vertical height of the mercury column in the glass tube remains unchanged.

The length and vertical height of the mercury column in the glass tube remain unchanged.

Change the length and vertical height of the mercury column in the glass tube.

7. A classmate estimated that the pressure of the surface atmosphere on a 0.28 square meter desk is about ().

a、2.8× 102N B、2.8× 103N

C 2.8× 104N D、2.8× 105N

8. As shown on the right, the measuring cylinder A is immersed in water, filled with water, with its mouth facing down, and lifted upward by grasping the bottom of the cylinder. The measuring cylinder is exposed to water before the cylinder mouth leaves the water.

Is this part empty or full of water? ______。

The reason for this phenomenon is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.

9. The change of atmospheric pressure is influenced by the weather. Please look for information or consult your parents and brothers to see if the air pressure becomes larger or smaller when it turns cloudy in sunny days. Is the atmospheric pressure greater in summer or winter? Why?

The second case of atmospheric pressure teaching plan

(A) teaching purposes

1. Understand the existence of atmospheric pressure.

2. Understand the principle of Torricelli experiment.

(2) The measurement of atmospheric pressure is the focus of teaching.

(3) Teaching process

First of all, introduce.

We learned about stress. Solid can produce pressure, liquid can produce pressure, so can gas produce pressure? Please read page 12 1 (two minutes).

1. Experiment. The earth where we live is surrounded by the air layer, the thickness of which is several Qian Qian meters. The air layer around the earth is called the atmosphere, and we live at the bottom of the atmosphere. We observe the pressure produced by air in the atmosphere through experiments. This is a teacup, full of water. Is there air in it? Cover the mouth of the cup with a piece of cardboard and gently turn the cup upside down. Look, why doesn't the cardboard fall down? Small pieces of paper must have been pressed out by the air in the atmosphere.

2. Experiment. This is a small porcelain jar used in acupuncture department of traditional Chinese medicine. This is a boiled peeled egg. If you put the egg in a jar, it won't fall. Now stick a piece of cotton on the inner wall of the jar filled with water, light the cotton with a match, and immediately put the egg on the jar mouth. What is the phenomenon of watching the police? (with the plate map) Eggs are put into the can. Eggs must bear a lot of pressure before they are pressed in. This pressure is the pressure of air in the atmosphere.

3. Experiment. A large test tube filled with water. Put this small test tube in the water of the big test tube. There is no water in the small test tube. Hold the small test tube with your index finger, turn the big test tube upside down and pay attention to the small test tube. The test tube rises. (matching board diagram). This experiment shows that there is pressure in the atmosphere.

Second, atmospheric pressure.

The above experiments show that there is pressure in the atmosphere. Another famous experiment-the experiment in the hemisphere of Madeborg proved the existence of atmospheric pressure.

1. Experiments in the hemisphere of Fort Madre. These are two metal hemispheres, which can be easily pulled apart after being closed. Now open the valve, pump out some air from both hemispheres, and then close the valve. Now invite two Hercules to watch (student operation). This experiment, the famous experiment in the hemisphere of Madeborg, strongly proves that the atmosphere is under pressure on the objects immersed in it. In the initial experiment of 1654, sixteen horses were needed to pull the hemisphere apart. Because the hemisphere is small and the vacuum is not high, sixteen horses are not needed to pull it away, but it is enough to prove that there is pressure in the atmosphere.

2. The pressure of the atmosphere on the object immersed in it is called atmospheric pressure, or atmospheric pressure for short. Everything around the earth is in the atmosphere, and they are all under atmospheric pressure. For example, the hemisphere of Fort Madre can't be pulled open, the eggs enter the jar, the small test tube rises, and the small pieces of paper don't drop, all of which are caused by atmospheric pressure.

Third, the magnitude of atmospheric pressure.

1. Experiment. Fill the test tube with water, block the opening with your index finger, and hang it upside down in the mercury tank (with attached plate) so that the water will not flow out. Please consider why the water doesn't flow out. (Ask questions, students answer) Water will not flow out because of atmospheric pressure. But the water in the test tube will also generate pressure. The water does not flow out not only because of the atmospheric pressure, but also because the atmospheric pressure is greater than the pressure generated by the water column in the tube. So how big is the atmospheric pressure? Before the famous hemispheric experiment at Fort Madre, Galileo's student Torricelli solved this problem.

2. Torricelli experiment. Take a glass tube about one meter long, with one end closed and one end open, and it is filled with mercury. There is no air in the pipe. Block the opening with your index finger and stand upside down in the mercury tank. Pay attention to the phenomenon in P 130 diagram 1 1-5. We first saw the mercury in the tube drop, and then stopped (there is a board diagram). Why does mercury drop? The atmosphere has pressure, but so does mercury. The pressure of mercury is greater than atmospheric pressure, so it falls. So, why stop now and stop falling? (Student answers) Atmospheric pressure is equal to the pressure of mercury column. So if you want to know the current atmospheric pressure, you need to calculate the pressure generated by this mercury column. According to the calculation method of liquid pressure in the previous chapter, assuming that there is a horizontal plane under the mercury column, the mass and gravity of the mercury column are calculated by measuring the height of the mercury column, and the pressure formula is used.

(operation). (The measured result is not necessarily 760 mm, but it can still be considered that the mercury column pressure is 105 Pascal).

It can be seen that the value of atmospheric pressure is equal to 105 Pascal, which is equal to the pressure generated by ×××××× mm Hg.

This experiment is the Torricelli experiment, which is used to measure atmospheric pressure.

3. Experiment. Now lift the glass tube slightly and observe the height of the mercury column. The result remains the same. Now tilt the glass. Notice how the vacuum volume on the surface of mercury changes. (Student answers) How does the length of the mercury column in the tube change? (The student answers). When inclined, the vacuum volume above the mercury level in the tube decreases and the mercury column becomes longer, but what is the height of the mercury column? (Measure and draw on the board) Obviously, the height of the mercury column in the tube is constant.

4. Ask questions and discuss with students. Please discuss how the height of mercury column in Torricelli's experiment changes if the atmospheric pressure increases or decreases due to weather changes. (Students answer after discussion) With the increase of atmospheric pressure, the height of mercury column in the tube increases; When the atmospheric pressure drops, the mercury column in the tube drops. Therefore, the height of mercury column varies with atmospheric pressure in this experiment, which provides convenience for us to measure atmospheric pressure. This is the reason for learning barometer in the future.

Fourth, summary.

We learned two things today. First of all, through a large number of experiments, especially the famous experiment in the Madeborg hemisphere, we fully realized the existence of atmospheric pressure. The second is to measure the atmospheric pressure. Torricelli experiment shows that the atmospheric pressure is equal to the pressure produced by mercury column in the test tube.

Verb (short for verb) homework

After class, please pay attention to the places or devices in your life that use the principle of atmospheric pressure, and give three examples each.