Geography teacher MBOU - secondary school No. 7 of the city of Mtsensk
Pikurova N.S.
Lesson type : learning new material
The purpose and objectives of the lesson:
expand existing knowledge about the main properties of sea water: temperature, salinity;
introduce students to new concepts;
continue the formation of the ability to work with a geographical map;
develop an interest in the subject.
develop research skills, the ability to analyze observed phenomena, formulate conclusions
Forms and methods: Explanatory and illustrative, partially exploratory; informational and illustrative; demonstration; independent work with the text of the textbook, conversation, work with the map.
Expected result of the lesson:
creative thinking of schoolchildren,
the ability to acquire knowledge from various sources,
analyze the facts
make a generalization
express their own opinions.
Equipment:
presentation of the lesson “Properties of the waters of the oceans”,
textbook “Geography. Beginner course” 6th grade,
atlas 6th grade,
physical map of the world;
multimedia projector, screen.
During the classes
I. Organizational moment.
– Good day! Guys, today we are again waiting for a journey through the endless world of the ocean. You will become members of the expedition of Captain Nemo, the hero of Jules Verne's novel "2000 Leagues Under the Sea".
II . Repetition. Checking homework.
But in order to travelCaptain Nemo has prepared a little test for you. The captain's boat will be waiting for you in the Indian Ocean at coordinates 30 Oyush and 80 Ovd. Each crew will try to get to this place from different points. We will draw lots. (Moscow, S.-P., Vladivostok) Crews led by captains are required to plan the navigation route of their ship in such a way as to cover the distance from the home port to the specified point in the shortest possible time. Route descriptions are recorded in the logbooks. (Time 4 min).
So, tell us about your routes.
III . Learning new material.
1 slide . All of you have successfully passed the test and the captain is glad to welcome you aboard his ship.
2 slide During our journey, you will learn about the properties of the world's oceans, such as salinity and temperature. We will conduct many observations and record the results in the logbook. So, let's go.
3 slide - Guys, you all know what water is. - What properties of water do you know?
4slide
Transparency
Has no smell
Fluidity
can simultaneously be in three states of aggregation
has low thermal conductivity
5slide - Also, water is a very good solvent, so ocean water is a solution of various substances. It contains 73 of the 110 known chemical elements. Sodium and chlorine, which form table salt, make up more than 85% of all substances dissolved in ocean water. Aluminum, copper, silver, and gold have been found in ocean water, but in very small quantities.
Ocean water also contains dissolved gases, including oxygen. Why is oxygen needed?(for the life of marine organisms)
Also necessary for life are calcium, silicon and phosphorus, which make up the shells and skeletons of marine animals.
Have you tried sea water? What does she taste like?(salty)
It is correct to say bitter-salty. The bitter taste of ocean water comes from magnesium salts.
6 slide - One of the properties of water is salinity.
Salinity is the amount of minerals in grams dissolved in 1 liter (1 kg) of water. It is expressed in ppm (thousandths of a number), indicated by the symbol ‰. Record the definition in your logbooks.
7 slide The average salinity of the World Ocean is 35 ‰. Let's try to bring the average salinity of ocean water in a liter jar. (It is necessary to add 35 g of salt).
Tell me, is there salt in the water you drink?
How to prove that there is salt in fresh water?(Salt can be seen by evaporating a few drops of water)
HeldEXPERIENCE. You need to drop a few drops of water on the glass and evaporate it by heating the glass on a spirit lamp. Salt will remain on the glass.
Also, scale remains at the bottom of pots and teapots - these are various salts.
The water is considered fresh1 liter of which contains less than 1 g of dissolved substances.
8 slide. Look at the map of the distribution of salinity in the world's oceans. Is the salinity of the water the same everywhere? (Not)
9 slide salinity distribution. You can see on the slide that the salinity in the seas is also not the same.
In the Red Sea, salinity is 42 ‰
salinity in the Black Sea - 18 ‰
Salinity in the Baltic Sea is 6-8 ‰
In the Gulf of Finland of the Baltic Sea, salinity is 3-4 ‰
In the Barents Sea, salinity is 35 ‰
Group work.
And now, try to bring the salinity of the ocean water of these seas.
1 crew - salinity of the Red Sea
2 crew - salinity of the Black Sea water
3 crew - salinity of the water of the Baltic Sea
Explain your actions. How did you get such salinity?
What problem do you think we will solve at the next stage? (Why salinity is different everywhere, what causes affect salinity?)
Guys, how can I change the salinity in my jar of water?
pour the water; 2) evaporate
Let's think about what processes in nature can pour water into the ocean?
( rain, rivers )
And what processes can remove water and leave salt? (Evaporation )
And where should you put a jar of water so that the water evaporates faster? (To a warm place ).
What other process can take water and leave salt?Ice )
10 slide - Let's conclude what factors affect the salinity of the oceans. (Salinity is affected by: precipitation, evaporation, number and fullness of rivers, ice formation ). Write it down in your logbooks.
11 slide. And now the crews do this task.
1 crew - explain why the Red Sea is the saltiest sea on Earth?
2 crew - explain why the salinity in the Black Sea is less than the average salinity of the ocean.
3 crew - explain why the salinity in the Baltic Sea is the smallest?
( Sample answer: In the marginal seas, the salinity is close to the average oceanic. Many rivers that carry fresh water flow into the Black Sea: the Dnieper, Don, Danube, etc. The Baltic Sea is located far from the equator, so there is little evaporation, many rivers that desalinate water flow into it. The full-flowing river Neva flows into the Gulf of Finland. Not a single river flows into the Red Sea, it is crossed by a tropic, which means there is little precipitation, and evaporation is large, because the sea is close to the equator )
Sailors learned about the approach of the coast by the salinity of the water. How could this be known?(Near the coast, the water is less salty, because rivers flow into the sea from the land, desalinating the water)
Why is the equator less saline than the tropics?(There is a lot of precipitation near the equator, little rainfall in the tropics)
12 slide - Look at the map, which ocean is the most salty?(Atlantic)
Which ocean has the least salinity?North Arctic )
13 slide. Average salinity of the oceans:
Pacific Ocean - 34.6%
Atlantic Ocean - 37.5%
Indian Ocean - 34.8%
Arctic Ocean - 32%
14slide - If all the salts dissolved in the waters of the World Ocean are evaporated and evenly distributed over the surface of the Earth, then our planet will be covered with a layer of salt 45 meters thick.
15 slide - Consider the following property of the waters of the World Ocean "Temperature".
Dear crew members, there was a disaster on the ship. In the captain's cabin there are all recorders from all instruments. The device that captures temperature changes at depth and on the surface of the water is out of order. It is urgent to draw graphs of changes in water temperature.
Group work.
1 crew - draw a graph of the change in water temperature on the surface, study the data on the temperature of the water and draw a conclusion about how it changes on the surface.
16 slide Surface water temperature:
0 c. br.: + 26С
30 s. br.: + 20С
60 s. sh. : + 5С
90 s. br.: - 1.5С
Conclusion : howfarther from the equator, the watercolder .
2 crew - draw a graph of the change in water temperature with depth. Examine the water temperature data and infer how the water temperature changes with depth.
0 m: + 20С
200 m: + 10С
1000 m: + 3С
2000 m: + 2С
5000 m: + 2С
Conclusion : temperature with depthgoing down . The water is heating upsunny rays. Rays only penetrateupper layers of water. Below a depth of 1000 m, the temperature remainsequally low . The sun's rays do not penetratedepth .
17 slide . So, let's summarize again, what does the temperature of the water depend on?
18 slide (from the climate) Record the output in your logbooks
3 crew - study the temperature distribution map over the surface of the water and say which of the oceans is the warmest, coldest and conclude why? Word 3 to the crew.
19 slide. The highest surface water temperature in the Pacific Ocean (+19.4°C), Indian (+17.3°C), Atlantic (+16.5°C) oceans, the lowest water temperature in the Arctic Ocean (-1 °C).
20 slide. The average temperature of the waters of the World Ocean is 3.5 ° С
On the surface of the ocean, the highest temperature was recorded in the shallow Persian Gulf of the Indian Ocean (above + 35С), the coldest water in the Weddell Sea in Antarctica - 1 - 2С.
Ocean water freezes at temperatures- 2С
The higher the salinity of water, the lower its freezing point.
IV . Lesson summary
What we learned today about the salinity and temperature of the waters of the oceans.
21 slide. Complete the sentences "I know that..."
salinity is measured in ppm
salinity in the seas and oceans is not the same
salinity depends on evaporation, precipitation, rivers flowing into the sea
fresh water has a salinity of 1 ‰
the most salty sea - Red
surface waters are heated by the rays of the sun
the deeper, the colder the water
the water temperature drops to a depth of 1000 m, then remains constant
the temperature near the equator is +26…+27С
at the poles the temperature is -1С
salt water freezes at -2°C
22 slide. V. Homework. § 26, ass. 3
23 slide. Lesson summary
