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Case-lesson “The World Ocean – the ocean of mysteries”
Case-lesson “The World Ocean – the ocean of mysteries”

Category: Science, nature and man

Level (grade): 5-9

Subject: Natural phenomena, geography and environment

Objective: To learn some information about seas and oceans, to see them in a new perspective, learn to find creative approaches to solving controversial issues.

What information is waiting for me here?

  • Are there mountains in the ocean?
  • Is it possible for a ship to “get stuck” in a sea?
  • How many centimeters the World Ocean gains each year?
  • How many species of marine organisms exist, are the new ones still being discovered these days?
  • Can we consider pirates the explorers of the seas?
  • Where does the price of canned fish come from?
6 scans of the subjects, phenomena and practices:

The World Ocean is the ocean of mysteries. It hides archaeological treasures in its depths. Under its waves the deepest canyons and the highest mountains of the world are hidden. Yet unknown to science fish and marine animals’ species live in the waters of the ocean; new, undiscovered species of algae grow there. Moreover, there are thousands of sunken ships on the ocean floor, concealing countless treasures, hunted by treasure seekers, who often succeed. By using modern bathyscaphes, navigational equipment, historical maps and archives, they find these treasures and develop a new kind of profitable adventure business.

Human’s curiosity is trying to disrupt the cover of these secrets. Science and modern technology make it possible to reveal the secrets of the ocean and solve yet unresolved underwater mysteries.


All oceans and seas of the planet constitute a united system with its own metabolism and energy. It has its own complex temperature regime, which largely affects the climate of the planet. There are no “superfluous details”. It cannot be “slightly contaminated”: any pollution, any change affects the system as a whole.


Sea is a part of the World Ocean, conditionally isolated by land or underwater terrain. There are many different classifications of seas, so their total number may vary. Conventionally, seas are assigned to the oceans, as well as the countries of the world are attributed to the continents. Overall, there are 5 oceans on Earth.

Seas can be divided into inland, marginal, intercontinental and interisland. Some scientists distinguish seas by the difference in salinity level, temperature of surface waters and shoreline irregularity if there is any.

Herewith, seas can be “special”: Caspian Sea, Aral Sea, the Dead Sea and the Sea of Galilee are considered to be lakes.

Sea of Galilee (a lake)

There are gulfs which are actually seas. For example, such gulf is the Persian Gulf – the gulf between Iran and the Arabian Peninsula. It is linked with the Gulf of Oman, Arabian Sea and Indian Ocean by the Strait of Hormuz. According to its hydrological regime it is the sea. Currently, there are debates about its title: some countries offer to call it the Arabian Gulf.

There are also seas, which are parts of other seas. For example, the Alboran Sea. It is the part of the Mediterranean Sea.

There are seas inside the ocean, bordered by the terrain or currents on all sides. For example, the Sargasso Sea. This is a part of the Atlantic Ocean, surrounded by currents on all sides: Gulf Stream, Northern trade wind (warm currents) and Canary (cold current). The borders of the sea are unstable and depend on seasonal changes of the currents’ borders. Moving clockwise, currents set cool waters of the North Atlantic apart of Sargasso Sea, thus the water temperature here does not fall below +18°C even in winter.


The name comes from the Portuguese word sargaso meaning “grapes”. The Spanish have called it the “sea of vines”. It has large concentrations of floating kelp – Sargassum, reserves of which within the sea are estimated at 4-11 million tons. Such huge number is connected with the presence of the convergence zone of surface currents in the Sargasso Sea.

The oddness of the Sargasso Sea has give rise to many legends. The most famous of them tells about the existence of algae clusters in the sea, in which ships stuck and sink. The legend is still occasionally repeated, despite the fact that sailors have never complained about the occurrence of any complications in the sea. Sailboats of the past centuries really had stuck in the Sargasso Sea, but not because of algae but frequent calm.

Currents form seas and climate. Sea currents are permanent or intermittent streams in the thickness of oceans and seas. There are permanent and periodic, irregular, surface and underwater, warm and cold currents.


The deepest point of the planet is located on the seabed, which is quite natural. There is the so-called “Challenger Deep” in the Mariana Trench. Its depth is 11 022 meters (according to other sources, differences up to 50 m are possible).


If there are gulfs, then there are also mountains. Parts of the underwater ridges, which stick out of the water, form islands, sometimes whole archipelagos.



What are the closest to your country seas?

Seas and oceans are some kind of “pools” of the Earth. Water goes in them through the continental runoff (river runoff for seas) and the atmospheric runoff. At the same time water from the sea or ocean surface evaporates. The world water balance remains virtually unchanged. In global terms, only water levels change.

The World Ocean can be considered as a subject of the classical mathematical problem of “a pool and two pipes”.

The fraction of all water reserves of the planet in the World Ocean is 96% (1 338 million km³ of water). River runoff of all rivers of the planet is 37 thousand km³.


Volume of melting of glaciers is 2.8 thousand km³/year.

The evaporation from the surface of the World Ocean is 355 thousand km³. In reverse order, from air to sea, only 320 thousand km³ are returned. The remaining water (35 thousand km³) goes through complex cycle on land before returning to the ocean.

Water balance of the World Ocean is the next:


Therefore, the amount of water has changed by 1 338 004 800 – 1 338 000 000 = 4 800 km³ over a year.

How will this change affect the waters of the World Ocean?

The famous formula for calculating volume allows to estimate the average increase in the World Ocean’s water level (water lift). The area of the World Ocean is 361 000 000 km³. Then 4800/361 000 000 = 0.0000133 km = 0.0133 m = 1.33 cm/year, which doesn’t contradict reference data.

In the ХХ century the World Ocean’s water level increased by 17 cm (this value is suggested by scientists).

According to forecasts, by the year 2100 sea level will rise by 40 cm. As river runoff is a constant value, such increase is possible due to melting glaciers. How will this component of the balance of the World Ocean change?

Let’s use proportion. If the level is changed by 1.33 cm melting glaciers are 2 800 km³. At the level of 40 cm – unknown (denoted Y). According to the proportion, 1.33 : 40 = 2 800 : Y.

Then: Y = (40 x 2 800) / 1.33 = 84 210.5 km³. Thus the volume of all terrestrial glaciers is 25 million km³.

But even this rate of melting can fatally change Earth’s exterior.


Territories, marked with red-brown, can be flooded.


How much the melting of glaciers (m³) will change if the water level of the World Ocean rises by 5 cm?

The research of flora and fauna of the World Ocean is gaining velocity. Discoveries that overturn the understanding of the underwater world appear.

For instance:

Known species of marine organisms are classified and divided into groups.

The seas and oceans of the planet are inhabited by 228 450 species of living organisms, approximately 86% of which are marine animals. These are more than 18 thousand fish species, which have been being tracked since the mid 1700's, more than 1 800 sea stars, 816 squids, 93 whales and dolphins and 8 900 molluscs. The last species are algae and other plants, bacteria, viruses, fungi and unicellular organisms.

An international team of scientists has been engaged in compiling the World Register of Marine biological species for the past 8 years. During their work the scientists have discovered more than 1 000 species of marine fish (on average 10/mo). The list describes 122 new species of sharks and stingrays, 131 new species of the family Gobiidae. In 2014 alone 1 451 new species of marine creatures were discovered and described, which means that the scientists were making an average of 4 discoveries per day. The database was supplemented with 2 new sub-species of dolphins: Australian humpback Sousasahulensis and freshwater Iniaaraguaiaensis, living in Araguaia River:


Plankton creates a separate special group. The term “plankton” comes from the Greek word “planos”, which means “wandering”. Plankton is the collective term for a community of inactive or drifting plants and animals, living in sea and fresh water.


Phytoplankton includes all plant organisms – from the tiny single-celled ones to giant algae. Plants, belonging to this group, recycle inorganic nutrients into organic matter due to their ability to photosynthesis. 90% of the whole plant kingdom of Earth is phytoplankton.

Zooplankton includes animal forms of plankton, which are the major consumers of phytoplankton. In its turn, zooplankton is food for many fish species, cephalopods molluscs and baleen whales.

Marine organisms exactly are “the foundation of life on Earth”, despite their tiny sizes. They regulate metabolic processes in the biosphere by taking part in all biogeochemical cycles.


For the biosphere, as well as for Earth as a whole, each organism, no matter how small, is important. This is even truer for organisms of the World Ocean as 90% of the planetary biomass consists of them.


What large marine animals do you know?

The history of ocean and sea studies is the history of the study of civilization. Most of the great geographical discoveries are somehow related to sea journeys and research.


Some discoveries have been made “accidentally”. These “researchers by accident” had been Vikings, pirates, sailors, merchants. For example, Francis Drake, who was the English navigator, corsair, Vice Admiral (1588). At the same time, he was the first Englishman who went for a trip around the world (1577-1580).


Pirates used to map the seas and oceans. Although these maps were used mainly for laying a course and as guidance to “pirate treasures”, convenient bays and harbors, they have historical and geographical value. Much important data is reserved in logbooks:


What is the difference between corsairs, privateers, filibusters and pirates?


The majority of pirates of the Caribbean were corsairs. In today's world the “pirate tradition” still exists. A striking example is the Somalia pirates.

They appeared in the waters of Somalia in the 90th. They mostly consisted of fishermen who had lost their jobs as a result of the civil war. Gradually pirate “gangs” have enriched themselves with militants.


No military operations had managed to deal with the pirates. And then the ruling dynasty of Abu Dhabi Al Nahyan developed a plan. They took Puntland, a province of Somalia with the population of 1.5 million people, under wing and hired a former CIA agent as an advisor. He formed a private army in that province with the most modern equipment: boats, airplanes, helicopters. In addition, the world's largest prison for pirates (up to 500 criminals) was opened in the province. That’s how piracy in that region was over.

Atlantis – the mythical city-state in the depth of the ocean – is of particular interest for contemporary adventure seekers. There is a large number of hypotheses, dedicated to Atlantis. Most of them can be reduced to 5 basic versions:


Discovery of Atlantis can become one of the biggest events of the twenty-first century. Contemporary equipment and research methods should give new impetus to the search for Atlantis. For example, in early 2009 after the launch of a new service called Ocean on GoogleEarth, designed for viewing the seabed topography, several users detected a specific image that resembles a snapshot of streets from a great height at the bottom of the Atlantic Ocean between the Strait of Gibraltar and the Azores archipelago (coordinates: 31°15'15" eastern latitude, 24°15'15" west longitude). On this occasion articles in many tabloids were published. Then Google immediately denied that information about Atlantis, stating that the image was a product of data collection and straight lines were the courses of ships, conducting bathymetric survey. Let’s hope that the appearance of the next notification of Atlantis won’t become a “false start” once again.

An important task for modern humanity is to leave such mark in the history of seas and oceans of which we will not be ashamed when facing the future generations.


Do you believe in the existence of the Atlantis? Who are the Atlanteans?


Oceans conceal so many mysteries and so much dynamics, and it usually attracts attention of artists. Look at these pictures: what feelings and emotions are you experiencing? Which of them is the closest to your current mood?


Dark blue, turquoise, light blue, ultramarine, electric, indigo, snow white – these are only a fraction of all paints that animate waves on paintings of marine artists. A branch of fine art, which depicts a sea or sea battle, is called the marina. This is a kind of landscape art.

The most famous marine artists of the world are William Turner and Ivan Konstantinovich Aivazovsky.

A marine artist is not just a theatrical character, genre affiliation. In France there is an official title of “Artist of the Navy”, to which outstanding marine artists are awarded by the Defence Minister. Not only artists can be awarded to this title but also photographers, illustrators, engravers and sculptors.


Where does the price of canned fish come from? Why do they cost exactly this sum of money – not greater and not smaller? The answer lies in the “components” of this price:


This is why the price is formed not only of the price for raw materials and production costs, but also of logistics, trading margins and taxes.

Accelerated and interactive methods

1. «Droplet drawing» (For the case-lessons “Pools – empty and full”, “Secrets of water”)

The essence of the task: One droplet of water can help create real masterpieces. This will require album paper sheets (according to the number of students), conventional straws for drinks and containers with water, tinted in different colors.

First of all dribble a droplet of water onto the sheet, and then… blow on it through the straw, forcing it to run in a desired direction. This is way, using the straw-brush and droplets of tinted water, we can draw a picture.

You can then arrange an exhibition of works and even choose the best of them.

OBJECTIVE: To revitalize, mobilize children, “turn on” good mood and positive thinking, train coordination and concentration.

2. «Droplets race» (For the case-lessons “Pools – empty and full”, “Secrets of water”)

The essence of the game: This game will require the same straws and tinted water. You can play in teams or even arrange the “Olympics” with 1/8-, ¼-, ½-finals and the finale. Students will have to draw tracks on the sheets – draw boundaries. Each participant chooses the color of their droplet. Droplets are put at the start – the beginning of the “tracks”. At the “Go” command students begin blowing on their droplets through the straws, droplets “run”, leaving a colored trace.

Droplets, which have finished faster, go to the next round. During the race it is allowed to “add” droplets but only onto the same spot where the previous droplet has stopped.

In the next rounds participants must use droplets of the same color, which they have used in the previous one. This way, step by step, the “champion droplet” will be determined!

OBJCETIVE: To revitalize, mobilize children, “turn on” good mood and positive thinking, train coordination, concentration and skills in strategic planning and tactical implementation.

Lesson’s summary:





The results of the case-lesson can be complemented with findings of students


What three websites have helped find important information?





To help student and couch:







Where can you get information for the case?


Географія: http://www.internevod.com/rus/atlas/geogr/03/more2.shtml



Біологія: http://www.divetravels.ru/pages/seaanimals/Default.aspx


Бізнес: http://www.gb.by/izdaniya/glavnyi-bukhgalter/zubko-l-formirovanie-tsen-na-rybu-i-more_0000000


Location of the lesson:

The case-lesson takes place in the classroom. It is possible to conduct the lesson at museum or library.



Teams of boys and girls.

The score was:….

The tasks for them:

  1.      In a year melting of glaciers increased on 3 thousand km³.

Under these conditions, how severely will the level of the World Ocean rise?

  1.      Which of the teams will name more seas, currents, islands, straits, marine animals?



Formulate five questions to the case-lesson (an individual task).



90 min (double lesson)  


The possibility to conduct the lesson with a student-understudy:



Gained knowledge and acquired competence:

The ability to quickly find the required information on the topic.

Gaining practical skills in application of acquired information.

Obtaining specific knowledge in mathematics, biology, geography and other areas (given in the scans).



Currents, underwater ridges, gutter, zooplankton, phytoplankton, river runoff, precipitation, glaciers.



Hrabowska Larysa Leonidivna


Participated in the case upgrading:


The End

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