Goals:
- introduce the composition and properties of air, introduce the concept of “atmosphere”;
- consolidate ideas about gaseous substances;
- develop the ability to pose problematic questions;
- cultivate a culture of communication, the ability to work in groups;
Lesson type: learning new material.
TCO: projector, screen, computer.
Equipment:
- equipment for conducting experiments;
- presentation (Appendix 1);
- textbook A.A. Pleshakova “The World Around Us”, grade 3, part 1;
- workbook A.A. Pleshakov on the world around us, part 1;
- plastic bags, syringes
Lesson progress
I. Organizational moment. Repetition of covered material
– Good afternoon my nature lovers. Today we will continue to learn the mysteries of our surrounding world. We will determine the topic of the lesson by solving a crossword puzzle. (slide 1)
- Science of substances (chemistry)
- It can be used to detect starch (iodine)
- Citric, formic, oxalic, lactic... (acid)
- Acid used to make canned food (vinegar)
- Vegetable from which sugar is obtained (beets)
- Type of sugar (glucose)
II. Lesson topic message
(slide 2) Lesson topic “Air and its protection”
(slide 3)-What do you know about air?
– What do you want to know?
III. Work on the topic of the lesson
1. What is air.
Air is "invisible". We don't see it, but we know that it is all around us. We can see air movement when we blow bubbles or fan ourselves. We can easily verify the reality of the existence of air by performing simple experiments:
- Fill a plastic bag with air, tie it, and try to squeeze it gently.
– Does it shrink easily?
- Fill a small syringe without a needle with air. Pinch the inlet hole with your finger. Try moving the piston.
– Is it possible to compress air?
– What happens if you let go of your finger?
(slide 4) The entire planet Earth is shrouded in an invisible transparent blanket - air. Air is everywhere - on the street, in the room, in the ground, in the water. Any free space on Earth is filled with air. Air is invisible, but it can be detected using our senses, which is what we did now.
Wind is the movement of air. The layer of air surrounding us and our planet is called atmosphere. (slide 5). The atmosphere is a gigantic shell of air that extends upward for hundreds of kilometers. The thickness of the atmosphere varies in different parts of the planet.
The Earth's air envelope is often called the Fifth Ocean. Is the Fifth Ocean really necessary for the Earth?
– People, plants and animals live at the bottom of the air ocean. Without air, emptiness and silence would reign forever on the globe. If the Earth lost its air, it, like the Moon, would be only a lifeless celestial body.
(student reading the poem “Air”)
Air
He is transparent and invisible
Light and colorless gas.
With a weightless scarf
It envelops us.
He is in the forest - thick, fragrant,
Like a healing infusion,
Smells of resinous freshness,
Smells of oak and pine.
In summer it is warm,
It blows cold in winter,
When frost paints the glass
And lies on them like a border.
We don't notice him
We don't talk about him
We just breathe it in -
After all, we need him.
– This poem talks about the composition of air and some of its properties.
2. Composition and properties of air
– So what is air? This is a gas, or rather, a mixture of gases (slide 6). Just 2 centuries ago, scientists learned that air is a mixture of many gases, mainly nitrogen - 78%, oxygen - 21% and carbon dioxide - 1%.
– Open the workbook page 18 and restore the diagram (slide 7), writing down what gaseous substances are included in the air? Underline the name of the gas that living beings absorb when breathing.
– What properties does air have? (slide 8)
- Now we will do an experiment to find out one more property of air. To verify this, you can do the following experiments:
Experience 1
– Let's take a flask with a tube. Let's put the tube in the water. Note that water does not enter the tube - air “does not let it in.” We will heat the flask.
What's happening?
– Air bubbles began to come out of the tube.
Why was this possible?
– This experiment shows that air expands when heated.Experience 2
–Place a cold, damp cloth on the flask. Why am I doing this? What do we see?
– We see how the water rises through the tube. The air seems to give up some of its space to the water. This happens because air compresses as it cools.When heated, air expands and when cooled, it contracts.
- Air is a poor conductor of heat.
Air has another interesting property - it conducts heat poorly. Many plants that overwinter under snow do not freeze because there is a lot of air between the cold snow particles, and the snowdrift resembles a warm blanket covering the stems and roots of plants.
– In autumn, the squirrel, hare, wolf, fox and other animals molt. Winter fur is thicker and more luxuriant than summer fur. More air is retained between the thick hairs, and animals in the snowy forest are not afraid of frost.
– The gray wolf has a large, fluffy tail. When the animal goes to sleep right in the snow, it covers its nose and paws with its bushy tail.
“And even in the most severe frosts, a fox is not cold in a snowy bed, because she covers herself, like a warm blanket, with her tail, between the long hairs of which there is a lot of air that does not allow the cold to pass through.
“And in winter, thick, thick fur grows on the red beauty’s paws, it seems as if the fox was wearing warm mittens.” She is not afraid to walk on snow and ice.
– Vole mice hide in holes under high snowdrifts, it’s warm and cozy there.
- And some birds - black grouse, capercaillie - burrow into deep snow in the bitterest frosts. It's warmer this way. There is even a poem about this:
January is blowing cold,
Hazel grouse, black grouse, capercaillie
Buried deep in the snow.
It warms them like fur.What property of air explains these facts? (air is a poor conductor of heat)
We know that air is everywhere - on the street, in the room, in the ground, in the water.
– Raise the notebook, can you see other objects through it?
- No.
– Can we see the next class through the wall?
- No.
– Do you see the objects that are in the classroom?
- Yes.
– What property of air does this indicate?
The air is clear. This is evidenced by the fact that we see all surrounding objects through it.
– Look at the indoor plants. What color are they?
- Green.
– What color is the school desk?
- Brown.
-What color is the air?
- He colorless.
–
That's right, this is another physical property of air.
Have you noticed that different rooms smell differently?
– In the canteen, hairdresser, pharmacy, particles of odorous substances mix with air particles, and we smell different odors. Does the air smell clean?
– Clean air does not smell.
The air has no smell.
Physical education minute
We'll rest a little
Let's stand up and take a deep breath.
Hands to the sides, forward.
The bunny is waiting at the edge of the forest.
The bunny was jumping under the bush,
Inviting us into your home.
Hands down, on the belt, up,
We are running away from everyone.
Let's run to class quickly.
We'll listen to the story there.
Questions Why?(slide 9)
- Why do birds sit ruffled in extreme cold?
- Why do houses have double glazing for the winter?
- How do you understand the expression: “The air must be clean!”
– There should be more oxygen and less carbon dioxide in the air. When we breathe, we absorb oxygen and release carbon dioxide. A person needs 600 liters of oxygen to breathe for just one day! But plants, on the contrary, absorb carbon dioxide in the light and release oxygen into the atmosphere. It’s not for nothing that plants are called the lungs of our planet. What wonderful air in the forest! It contains a lot of oxygen and nutrients. After all, trees emit special volatile substances - phytoncides, which kill bacteria. The resinous smells of spruce and pine, the aroma of oak, birch and larch are very beneficial for humans.
But in cities the air is completely different, polluted. Can you explain to me what or who this is connected with?
Sources of pollution: (slide 10)
- factories and factories emit poisonous gases, soot, dust from their chimneys,
- cars emit exhaust gases, which contain a lot of harmful substances,
- fires, volcanic eruptions,
- land pollution with unprocessed waste.
Air pollution threatens human health and all life on Earth!
What should people do to keep the air clean? Using the textbook text on page 47, find ways to solve this problem. (slide 11)
IV. Reinforcing the material learned
Test “Air. His security"(slide 13,14)
- What substances make up air?
A. hydrogen, copper, zinc
B. oxygen, nitrogen, carbon dioxide
B. chlorine, fluorine, iodine - What air gas is needed for breathing?
A. nitrogen
B. oxygen
B. carbon dioxide - What properties does air have?
A. Transparent, colorless, odorless, when heated expands and contracts when cooled, bad conducts heat
V. Blue, like the sky, conducts sounds, allows sunlight to pass through and is odorless - Double frames are installed in the windows to retain heat. What property is being used?
A. When heated, air expands
B. As air cools, it compresses.
B. Air is a poor conductor of heat. - How should we protect air from pollution?
A. Stop all factories and factories, stop logging. Prohibit the use of motor vehicles. Turn the Earth into one huge reserve.
B. Factories and factories must have dust and harmful substance traps. Transport must be made environmentally friendly. Create belts of gardens, parks and forests in and around cities.
Answer:(slide 15,16)1. B, 2. B, 3. A, 4. B, 5. B
He is transparent and invisible
Light and colorless gas.
With a weightless scarf
It envelops us.
We don't notice him
We don't talk about him
We just breathe it in -
After all, we need him.
(slide 18) For the health of people and all life on Earth, we need clean air. After all, only clean air gives LIFE!
(slide 19)Homework: pp. 44-47, read, answer questions, workbook p. 20 No. 5.
Friction with the air, of course, occurs, and at the same time a certain amount of heat is released, but another physical process called aerodynamic heating heats up the skin of the descent vehicle and causes fireballs flying towards the ground to burn and explode.
As is known, a shock wave is formed in front of a body moving in a gas at supersonic speed - a thin transition region in which a sharp, abrupt increase in the density, pressure and speed of the substance occurs. Naturally, as the gas pressure increases, it heats up - a sharp increase in pressure leads to a rapid increase in temperature. The second factor - this is actually aerodynamic heating - is the braking of gas molecules in a thin layer adjacent directly to the surface of a moving object - the energy of the chaotic movement of molecules increases, and the temperature rises again. And the hot gas heats up the supersonic body itself, and the heat is transferred both by thermal conductivity and by radiation. True, the radiation of gas molecules begins to play a noticeable role at very high speeds, for example, at the 2nd cosmic speed.
Not only spacecraft designers have to deal with the problem of aerodynamic heating, but also developers of supersonic aircraft - those that never leave the atmosphere.
It is known that the designers of the world's first supersonic passenger aircraft - Concorde and Tu-144 - were forced to abandon the idea of making their aircraft fly at a speed of Mach 3 (they had to be content with “modest” 2.3). The reason is aerodynamic heating. At such a speed, it would heat up the skins of the airliners to such temperatures that could already affect the strength of aluminum structures. Replacing aluminum with titanium or special steel (as in military projects) was impossible for economic reasons. By the way, you can read about how the designers of the famous Soviet high-altitude interceptor MiG-25 solved the problem of aerodynamic heating in
1. On your own or with the help of a textbook, label on the diagram what gaseous substances are included in the air.
Mark with pencils of different colors (of your choice) which gas living beings absorb and which they emit when breathing.
Decipher the symbols you used:
2. Based on the research results, fill out the table.
3. Use a schematic diagram to show how air particles arrange themselves when heated and cooled. (Denote air particles with circles.) 
Wise Turtle and complete her tasks.
Air is the protector of living things
Herbaceous plants overwintering under snow do not freeze because there is a lot of air in it. Thanks to the air, cold snow serves as a warm “blanket” for plants.
By winter, animals' fur becomes thicker, and birds' feathers become thicker. More air is retained between thick hairs and feathers, and the animal is warmer in winter.
1) These facts are explained by another property of air, which we have not yet talked about. Think about what this property is - air does not conduct heat well.
2) Give an example proving that this property of air is important not only for plants and animals, but also for humans - there is air between the body and a person’s clothes and in the clothes themselves, so clothes retain the heat of our body
Test yourself.
5. Come up with and draw a poster “Take care of the air!” on a separate sheet of paper.
Look what your friends have drawn. If you have ideas on how you can help protect the air, discuss them and do it.
6. According to the instructions in the textbook, find out and write down what is being done in your city to protect the air.
In our city, to protect the air, enterprises install filters on pipes, and trees are planted in parks and forests. New transport interchanges are also being built in the city to eliminate traffic jams.
LESSON SUMMARY ON THE ENVIRONMENT
FOR 3rd CLASS.
Educational and educational complex "School of Russia"
Subject: Air and its protection.
Objective of the lesson:
To introduce students to the composition and properties of air.
Tasks:
- educational:
to develop knowledge about the importance of air for all living things
Earth;
in the process of experiments and practical work to form knowledge
about the basic properties of air;
develop practical skills to work with laboratory materials
equipment, conduct experiments, conduct observations;
analyze, summarize and draw conclusions based on the results of observation
Denium;
learn to work with a hypothesis (assumption throughactive method
and practical approach).
Educational:
create conditions for the student’s personal development; revitalization
independent activity and group work; development method-
ability to constructive creativity, observation, ability to compare
draw conclusions;
- educational:
create conditions for instilling respect for the environment
environment;
create conditions for developing a communicative culture, skills
work in groups, listen to and respect the opinions of others;
feelings of mutual assistance and support.
Equipment: for students: textbook “The world around us, grade 3” by A.A. Ple-
Shakova; workbook; magnifying glass, wood leaf
from the teacher: textbook, workbook, presentation, electronic supplement
textbook; plastic bag, laboratory equipment: flask, alcohol lamp,
cloth for experiment, magnifying glass, leaf of wood, computer, presentation, multimedia
new projector, screen.
PROGRESS OF THE LESSON.
I. Organizational moment (2 min)
Checking seating and readiness for class.
Today in class you will work in groups. What rules of working in a group must be remembered and followed?
(Work to the best of your ability; listen to everyone
each group member attentively, without interrupting;
speak clearly and to the point; support your comrades;
if you don't agree with someone, say it politely,
choose as captain the one who can choose
the best solution together with everyone; remember: perform
It’s an honor to die on behalf of the group)
II. Updating knowledge. Checking homework. (4 min)
Target: consolidation of knowledge acquired in previous lessons
( Presentation ):
Summary of the stage.
III. Self-determination for activity. (1 min)
Guess the riddle:
Passes through the nose into the chest
And the return is on its way.
He's invisible, but still
We cannot live without him.
(Air)
How did you guess?
(We breathe air, we cannot live without it,
but we don’t see it)
What do you think will be discussed in class today?
(About air, its composition and properties)
IV. Work on the topic of the lesson (20 min)
Conversation
There are 5 oceans on our planet. What are they called?
(Arctic, Pacific, Atlantic, Indian and Southern)- There is another very important ocean in the world - the largest, and every day, every hour, every minute, without noticing it, we “swim” in it. What is the name of this ocean? (Air)
The ocean of air has its own scientific name. Our students will tell you more about this...
Student performance . Pre-prepared students make a presentation.
Target: working with educational, popular science texts accessible to primary schoolchildren, correct and conscious reading aloud. Construction of a monologue statement on a proposed topic, on a given question .
The layer of air surrounding our planet is called the atmosphere.
The atmosphere is a gigantic shell of air that extends upward for hundreds of kilometers. The thickness of the atmosphere varies in different parts of the planet.
The atmosphere protects the earth from excess heat and cold, and from excessive solar radiation. If it suddenly disappeared, then water and other liquids on Earth would instantly boil, and the rays of the sun would burn all living things.
The ocean of air - the atmosphere - is very important for life.
Can living things survive without air? (No)
Why? (You could suffocate and die)
Indeed, if you take a deep breath, cover your mouth and nose with your palm and count to yourself: one, two, three... Before you can count to 60, you will really want to take a breath of fresh air.
When a person goes underwater, climbs high into the mountains or flies into space, he should always have a supply of air with him.
If the ocean of air suddenly disappeared, our planet would become a lifeless planet in a few minutes.
Why is the air ocean so important? (Children's answers)
The air shell of the Earth is its amazing “shirt”. Thanks to it, the planet does not overheat from the sun's rays and does not freeze from the cosmic cold. This “shirt” protects the Earth from meteorite impacts. They simply burn in the air. So the Earth simply needs an air “jacket,” and only thanks to it does intelligent life exist on Earth, the only planet in the Solar System.
Is it possible to verify that air exists? What do you think?
(Children's answers)
It is very easy to verify that air really exists. Try waving your hand. How do you feel?
(Air movement)
I have an empty plastic bag in my hands. I'll wave it and pinch the ends. Why did the bag inflate and become elastic?
(There's air there)
What is the significance of air for humans, plants and animals?
(Air is necessary for breathing, protects the Earth from
overheating and cooling, from meteorites, from
harmful rays of the sun).
Well done!
Physical education minute (1 min)
We'll rest a little
Let's stand up and take a deep breath.
Hands to the sides, forward.
The bunny is waiting at the edge of the forest.
The bunny was jumping under the bush,
Inviting us into your home.
Hands down, on the belt, up,
We are running away from everyone.
(Running in place.)
Let's quickly run to class,
We'll listen to the story there.
Checking the fit.
Practical work “composition and properties of air”. Work in a notebook (pp. 27-29)
Target: teach children to observe, hypothesize, analyze and draw conclusions based on practical actions.
Read the poem. What can you learn about air from it?
(Air is a mixture of gases)
Open the textbook on page 46. Consider the “Composition of Air” diagram.
What gases are included in air?
(Oxygen, nitrogen and carbon dioxide)
What gas is in the air the most? (Nitrogen)
What gas is the least in the air? (Carbon dioxide).
People learned what composition air has only 200 years ago. Joseph Priestley and Antoine Lavoisier were the first to study the composition of air and its properties.
When living things breathe, they absorb oxygen from the air and release carbon dioxide.
Working in pairs
Cover your textbooks.
Open your notebooks on page 27 and complete task No. 1 yourself.
(On your own or with the help of a textbook, sign up for
diagram, what gaseous substances are included in the air
spirit. Mark with pencils of different colors (according to your preference)
boron), what gas living beings absorb when breathing,
and which one is highlighted. Decipher the devices you used
catchy designations).
Exchange notebooks and check each other's work. Draw a conclusion, evaluate the work.
Return the notebooks to each other. Test yourself using the textbook. Correct the errors. Evaluate your work. Select the desired icon:
Bottom line . – Who completed the task without errors?
Well done.
Who experienced difficulties during the task?
Correct your mistakes and pay more attention in class.
Guys, what properties does air have?
(The air is elastic, ... (children’s assumptions)
Let's do some experiments and see if you're right.
During practical work we will complete task No. 2 in the notebook.
Look at the table and tell me what questions we should answer as a result of our observations?
(Fill out the table based on the research results.
Properties of air
What we study
Conclusion
Is the air transparent or opaque?
Does air have color?
Does the air have a smell?
What happens to air when heated?
What happens to air when it cools?
- How do you think the first question should be answered? (children's answers)
What will help us prove this? (children's hypotheses).
- Guys, take the textbook, tell me, is it transparent?
Look at the door, is it transparent? Are others visible through these objects?
Why do we see a door, a textbook, a blackboard, a desk? Discuss and give your guesses.
( The air is transparent)
- Record the output in a table. (The air is clear)
What's the next question? (Does air have color?)
How can you answer this question? How to prove this?
(Children's statements)
(If the children find it difficult, the teacher prompts them)
- What color is the board? (Green)
What color is the cabinet? (Brown)
What color is chalk? (White)
What color is the air? (Has no color )
Record your findings in a table. (Air has no color).
Read the third question.
(Does the air have a smell?)
What can you guess? What evidence can we use?
(Children's statements)
(If the children find it difficult, the teacher prompts them)
Guys, raise your hand, which one of you wasin a hair salon, in a cafeteria, in a clinic? Imagine being asked to find out where you are with your eyes closed? Is this possible? How? Discuss and give your guesses.
( We can determine where we might be by smell. We know that odorous particles mix with air particles. Thanks to this, we smell. But clean air has no smell.)
Record the output in a table. (The air has no smell)
- WhatWhat happens to air when it is heated and cooled? We will find out this through experiments.
Experience No. 1.
Target: find out what happens to air when heated.
Let's take a flask with a tube. Let's put the tube in the water. What are we seeing?
(Water does not enter the tube; air does not let it in).
We will heat the flask. What happens now?
(Air bubbles began to come out of the tube.)
( Air expands when heated ) - entry in a notebook).
Experience No. 2.
Target: find out what happens to air when it cools.
Place a cold, damp cloth on the flask. What are we seeing?
(The water rises in the tube. The air seems to give way
water part of its place)
What conclusion can be drawn based on the observations?
( When cooling, air compresses) - notebook entry)
Air has another interesting property. In order to find out, let’s complete task No. 4 on page 28 in the workbook.
Read the story of the Wise Turtle and complete her tasks.
(One of the students reads the story aloud)
Think about what property of air is described in the story?
(Children's guesses)
Let's check ourselves. Read the text in the “Test yourself” section.
Well done!
So, what properties does air have?
(The air is transparent, colorless, odorless, when
When heated it expands and when cooled it contracts.
elastic, conducts heat poorly)
Well done!
V. Physical education minute (1 min)
To become strong and agile
Let's start training.
Inhale through your nose and exhale through your mouth.
Let's breathe deeply, and then
Step in place, slowly,
How nice the weather is!
We checked your posture
And they pulled their shoulder blades together.
We walk on our toes
And now - on the heels.
Checking the fit.
VI. Consolidation of the studied material. Work in a notebook (5 min)
Target: consolidate acquired knowledge
Read task No. 3 on page 28 in your notebook.
(Use a schematic diagram to show how the
relies on air particles for heating and cooling)
What properties of air must be taken into account in order to complete the task correctly?
(When heated, air expands, and when cooled,
Denia is shrinking)
How to explain that air expands when heated? What happens to the particles that make it up?
(The particles begin to move faster, and between
ki between them increases)
In the first rectangle, draw how air particles are arranged when heated.
How to explain that air compresses when cooled? What happens to the particles that make it up?
(The particles begin to move more slowly, between
the horrors between them are decreasing)
Draw in the second rectangle how air particles are arranged as they cool.
(After completing the task, a self-test is carried out on the slide:
VII. Reflection (4 min)
Group work
Read the second task on p.48. Complete it.
(Read the text “The air must be clean.” Find information in it: About the sources of air pollution; about ways to protect air purity.)
What pollutes the air?
(Plants and factories, cars)
What methods of air protection do you know?
(Installation for collecting soot, dust,
toxic gases, electric vehicles)
Conversation (5 min)
There is a factory in the city. Clouds of smoke poured out of its chimney day and night. Residents of the city coughed, sneezed, and some were even admitted to the hospital. They even wanted to close the factory, but how could they manage without goods?
One day, smoke stopped pouring out of the factory chimney. It soon became clear that smoke eliminators had been attached to the pipe, which prevented soot particles from flying out of the pipe.
And here's what's interesting. The soot is now carefully collected and sent to a plastics factory, where various plastic things are made.
In a word, everyone benefits from the smoke trap - both city residents, the factory (it sells soot), and plastic manufacturers.
Name ways to protect air purity.
(Air purification units, electric vehicles)
Can you somehow influence the cleanliness of the air?
(You can plant plants, they purify the air)
Why do plants absorb carbon dioxide and release oxygen?
(Children's guesses)
Let's take a close look at the leaf of the tree. The lower surface of the sheet is covered with a transparent film and dotted with small holes. They are called "stomata". They open and close, collecting carbon dioxide. In the light of the sun, sugar, starch and oxygen are formed from water that rises from the roots along the stems of plants and carbon dioxide in green leaves. That’s why plants are called “the lungs of the planet.”
VIII. Summing up the lesson. (2 min)
What is air? (Mixture of gases - nitrogen, oxygen and carbon dioxide)
Name the properties of air.
(The air is transparent, colorless, odorless, elastic,
expands when heated, contracts when cooled,
conducts heat poorly)
What new did you learn in the lesson?
IX. Homework (1 min)
Workbook: No. 5 (p. 29)
Air has another interesting property - it conducts heat poorly. Many plants that overwinter under snow do not freeze because there is a lot of air between the cold snow particles and the snowdrift resembles a warm blanket covering the stems and roots of the plants. In autumn, the squirrel, hare, wolf, fox and other animals molt. Winter fur is thicker and more luxuriant than summer fur. More air is retained between the thick hairs, and animals in the snowy forest are not afraid of frost.
(The teacher writes on the board.)
Air is a poor conductor of heat.
So, what properties does air have?
V. Physical education minute
VI. Consolidating the learned material Completing assignments in the workbook
No. 1 (p. 18).
- Read the assignment. Examine the drawing and label on the diagram which gaseous substances are part of the air. (Self-test with the diagram in the textbook on p. 46.)
No. 2 (p. 19).
Read the assignment. Write down the properties of air. (After completing the task, a self-test is carried out with notes on the board.)
No. 3 (p. 19).
- Read the assignment. What properties of air must be taken into account in order to complete the task correctly? (When air is heated, it expands; when cooled, it contracts.)
How to explain that air expands when heated? What happens to the particles that make it up? (The particles begin to move faster, and the gaps between them increase.)
In the first rectangle, draw how air particles are arranged when heated.
How to explain that air compresses when cooled? What happens to the particles that make it up? (The particles begin to move more slowly, and the spaces between them become smaller.)
- Draw in the second rectangle how air particles are arranged as they cool.
No. 4 (p. 19).
- Read the assignment. What property of air explains this phenomenon? (Air is a poor conductor of heat.)
VII. Reflection
Group work
Read the first task in the textbook on p. 48. Try to explain the properties of air.
Read the second task on p. 48. Follow through.
What pollutes the air? (Industrial enterprises, transport.)
Conversation
There is a factory not far from my house. From my windows I can see a high brick chimney. Thick black clouds of smoke pour out of it day and night, causing the horizon to forever hide behind a thick, serous curtain. Sometimes it seems as if this is a heavy smoker fuming the city with his unquenchable Gulliver pipe. We all cough, sneeze, some even have to be admitted to the hospital. And at least for the “smoker”: just puff and puff, puff and puff.
Children are crying: disgusting factory! Adults are angry: close it immediately!
And everyone hears in response: how so “nasty”?! How to “close” like that?! Our factory produces goods for people. And, unfortunately, there is no smoke without fire. If we extinguish the flames of the furnaces, the factory will stop and there will be no goods.
One morning I woke up, looked out the window - there was no smoke! The giant stopped smoking, the factory is in place, the chimney still sticks out, but there is no smoke. I wonder how long? However, I see: there is no smoke tomorrow, and the day after tomorrow, and the day after tomorrow... Has the factory really been closed down completely?
Where did the smoke go? They themselves said that there is no smoke without fire.
It soon became clear: they finally heard our endless complaints - they attached smoke eliminators to the factory chimney, a smoke trap that prevents soot particles from flying out of the chimney.
And here's what's interesting. It would seem that no one needed and even harmful smoke was forced to do a good deed. It (or rather, soot) is now carefully collected here and sent to a plastics factory. Who knows, maybe this felt-tip pen of mine is made from the same soot caught by smoke traps. In a word, smoke traps benefit everyone: us, the city residents (we no longer get sick), and the factory itself (it sells soot, and does not waste it as before), and buyers of plastic products (including felt-tip pens).
Name ways to protect air purity. (Air purification units, electric vehicles.)
- To clean the air, people plant trees. Why? (Plants absorb carbon dioxide and release oxygen.)
Let's take a close look at the leaf of the tree. The lower surface of the sheet is covered with a transparent film and dotted with very small holes. They are called “stomata”; you can only see them well with a magnifying glass. They open and close, collecting carbon dioxide. In the light of the sun, sugar, starch, and oxygen are formed from water that rises from the roots along the stems of plants and carbon dioxide in green leaves.
It’s not for nothing that plants are called “the lungs of the planet.”
What wonderful air in the forest! It contains a lot of oxygen and nutrients. After all, trees emit special volatile substances - phytoncides, which kill bacteria. The resinous smells of spruce and pine, the aroma of birch, oak, and larch are very beneficial for humans. But in cities the air is completely different. It smells of gasoline and exhaust fumes, because in cities there are a lot of cars, factories and factories are operating, which also pollute the air. Breathing such air is harmful to a person. To clean the air, we plant trees and shrubs: linden, poplar, lilac.