Oceans and Continents — Class 6 Social Science
Exploring Society: India and Beyond · Chapter 2
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5- Mathematics
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- Space weighted by chapter size
- Charts from the book's own data
- Traps corrected
- Space weighted by chapter size
- Charts from the book's own data
- Traps corrected
- Space weighted by chapter size
- Charts from the book's own data
- Traps corrected
- Space weighted by chapter size
- Charts from the book's own data
- Traps corrected
- Space weighted by chapter size
- Charts from the book's own data
- Traps corrected
Chapter summary
Key ideas & terms
- Ocean
- A very large body of salt water; there are five oceans, all interconnected.
- Continent
- A large continuous expanse of land; the most common count is seven continents.
- Island
- A piece of land smaller than a continent and surrounded by water on all sides.
- Marine flora and fauna
- The plant life (algae, seaweed) and animal life (fish, dolphins, whales) found in oceans.
- Tsunami
- A huge, powerful ocean wave usually caused by an undersea earthquake or volcanic eruption.
- Freshwater
- Water that is not salty, found in glaciers, rivers, lakes, the atmosphere and as groundwater.
Extra questions & answers
Why is the Earth called the ‘blue planet’?
Because almost three-fourths of its surface is covered with water, it looks mostly blue when seen from space.
Name the five oceans in order of size.
Pacific (largest), Atlantic, Indian, Southern (Antarctic) and Arctic (smallest).
Are the oceans really separate?
No. The boundaries shown on maps are only conventions; the oceans are interconnected and seawater flows freely between them.
Which seas lie on either side of India?
The Arabian Sea lies to the west and the Bay of Bengal to the east of India, both parts of the Indian Ocean.
How many continents are usually counted, and which count is most common?
Continents can be counted from four to seven; the seven-continent count is the one most widely used.
Name India's two major groups of islands.
The Andaman and Nicobar Islands in the Bay of Bengal and the Lakshadweep Islands in the Arabian Sea.
Why are oceans called the ‘planet's lungs’?
Because more than half of the world's oxygen is produced by the flora (such as algae) living in the oceans.
How do oceans bring rain to the continents?
Clouds form over the oceans and carry moisture inland; in India the summer monsoon rains originate in the ocean.
What is the largest island in the world?
Greenland is the largest island in the world.
How are oceans being harmed by human activity?
Oceans are polluted by millions of tonnes of plastic waste each year and harmed by overfishing, which threaten marine life.
The Big Questions
1. What are oceans and continents? What are their names and their distribution?
Oceans are the largest continuous bodies of salty water that cover about seven-tenths or almost three-fourths of the Earth's surface. Continents are large continuous expanses of land that cover a little over one-fourth of the Earth's surface. There are five oceans - the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, the Southern or Antarctic Ocean and the Arctic Ocean - and seven continents - Asia, Africa, North America, South America, Antarctica, Europe and Australia in the most widely used count. They are not equally distributed: the Northern Hemisphere has more land and the Southern Hemisphere has much more water. All oceans are interconnected as one global ocean and together they surround the continents.
2. In what ways do oceans and continents impact life on Earth, including human life?
Oceans and continents shape climate and regulate temperature and rainfall. Oceans bring monsoon rains through the water cycle and without them the Earth would be a desert. Oceans produce more than half the world's oxygen through marine algae and are called the planet's lungs. They support rich marine flora and fauna from algae and coral reefs to fish, dolphins and whales. For humans, oceans have provided routes for migration, trade, fishing and food, and have inspired cultures, legends and worship such as Varuna. They can also cause disasters like cyclones and tsunamis. Continents provide the land where humans, plants and animals live and where agriculture, settlements and civilizations develop.
LET'S EXPLORE
What are the circular lines in each map called? And do you know what the lines radiating out of the two poles are called? (Hint: you studied them in the previous chapter, but here they are presented differently.)
The circular lines centred on the North Pole and South Pole are parallels of latitude. They are circles running east-west around the Earth parallel to the Equator. The lines radiating out from the poles are meridians of longitude. They run north-south and meet at the poles.
Which hemisphere holds more water?
The Southern Hemisphere holds much more water than the Northern Hemisphere. When seen from above the South Pole, almost the whole view is ocean with only Antarctica and small parts of other continents, while the view from above the North Pole shows much more land.
What do you think could be the approximate proportion of water to land in the Northern Hemisphere? And in the Southern Hemisphere? Discuss in groups.
For the whole Earth the proportion is about
Are all the oceans connected with one another, or are there separations between them?
All the oceans are connected with one another. They form one continuous global ocean. The boundaries shown on maps between the Pacific, Atlantic, Indian, Southern and Arctic Oceans are only conventions drawn by humans. In nature seawater, marine life and currents flow freely from one ocean to another.
THINK ABOUT IT
If there is such abundance of water on the planet, why is there so much talk of ‘water scarcity’ or a ‘water crisis’?
Although almost three-fourths of the Earth is covered with water, about
What ways of saving water are you aware of? Which ones have you seen practised at home, at your school, and in your village, town or city?
Ways to save water include closing taps when not in use, fixing leaking taps and pipes, using a bucket instead of a shower, reusing water, rainwater harvesting, drip irrigation for plants, not wasting water while brushing or washing, and storing water carefully. At home this can be seen as turning off taps, repairing leaks and using buckets. At school it can be seen as closing taps in washrooms, rainwater harvesting tanks and watering gardens in the morning or evening. In villages, towns or cities it can be seen as Jal Jeevan Mission pipes, rainwater pits, tanks, and awareness campaigns to save water.
LET'S EXPLORE
Locate the five oceans and, in the table below, mark the hemisphere or hemispheres they belong to. Pacific Ocean
Pacific Ocean belongs to both Northern Hemisphere and Southern Hemisphere. It lies on both sides of the Equator and extends from the Arctic in the north to the Southern Ocean in the south.
Locate the five oceans and, in the table below, mark the hemisphere or hemispheres they belong to. Atlantic Ocean
Atlantic Ocean belongs to both Northern Hemisphere and Southern Hemisphere. It stretches from the Arctic Ocean in the north to the Southern Ocean in the south across the Equator.
Locate the five oceans and, in the table below, mark the hemisphere or hemispheres they belong to. Indian Ocean
Indian Ocean belongs to both Northern Hemisphere and Southern Hemisphere, but most of it lies in the Southern Hemisphere. It is bounded by Asia to the north, Africa to the west, Australia to the east and the Southern Ocean to the south.
Locate the five oceans and, in the table below, mark the hemisphere or hemispheres they belong to. Southern Ocean
Southern Ocean belongs to the Southern Hemisphere only. It surrounds Antarctica around the South Pole.
Locate the five oceans and, in the table below, mark the hemisphere or hemispheres they belong to. Arctic Ocean
Arctic Ocean belongs to the Northern Hemisphere only. It surrounds the North Pole.
LET'S EXPLORE
Counting the numbers of squares, name the largest continent and the smallest.
By counting squares in the diagram, Asia covers the most squares and is the largest continent, while Australia covers the fewest squares and is the smallest continent. This matches the real world where Asia is about
Which one is larger — North America or South America?
North America is larger than South America. In the diagram North America covers about
Which one is larger — Africa or North America?
Africa is larger than North America. In the diagram Africa covers about
Which one is larger — Antarctica or Australia?
Antarctica is larger than Australia. In the diagram Antarctica covers about
Re-colour the diagram by having a single colour for Europe and Asia and rename the result as ‘Eurasia’. Compare its size with South America’s.
If Europe and Asia are coloured together as Eurasia, they together cover about
Write down the list of continents from the smallest to the largest.
From smallest to largest the continents are: Australia, Europe, Antarctica, South America, North America, Africa, Asia. If counting by squares in the diagram the order is the same: Australia
Questions, activities and projects
1. Explain the following terms: (a) Continent
A continent is a large continuous expanse of land on the Earth's surface. It is much larger than an island and is generally surrounded by water. There are seven continents in the most widely used count: Asia, Africa, North America, South America, Antarctica, Europe and Australia. Together they cover a little over one-fourth of the globe.
1. Explain the following terms: (b) Ocean
An ocean is the largest continuous body of salty water covering the Earth's surface. Oceans together cover about seven-tenths of the planet and hold most of its water. There are five oceans: Pacific, Atlantic, Indian, Southern and Arctic. They are all connected and form one global ocean whose water, currents and marine life move across conventional boundaries.
1. Explain the following terms: (c) Island
An island is a piece of land smaller than a continent that is surrounded by water on all sides. There are lakhs of islands of many sizes. For example, Greenland is the world's largest island, and India has more than 1,300 islands including the Andaman and Nicobar Islands in the Bay of Bengal and the Lakshadweep Islands in the Arabian Sea.
2. Let us draw – Without looking at the maps in this chapter, draw the continents free hand on a sheet of paper and colour them. Then compare your drawing with the map of oceans and continents in the chapter.
This is a practice activity. Draw a rough world map from memory showing the seven continents in their approximate positions: North America and South America in the west, Africa and Europe above South America, Asia to the east of Europe, Australia southeast of Asia and Antarctica at the bottom. Colour each continent differently. Then compare with Fig. 2.3 to check shapes, relative sizes and positions, and correct errors like placing Australia or Antarctica. The aim is to improve map memory and understanding of distribution.
3. Let us do – On the outline map of the world given below, label all the continents and oceans.
On the outline world map label: Continents - Asia in the northeast, Europe west of Asia, Africa south of Europe, North America in the northwest, South America south of North America, Australia southeast of Asia, Antarctica at the south pole. Oceans - Pacific Ocean between Asia/Australia and the Americas, Atlantic Ocean between the Americas and Europe/Africa, Indian Ocean between Africa, Asia and Australia, Southern Ocean around Antarctica, and Arctic Ocean around the North Pole. The Arabian Sea and Bay of Bengal are parts of the Indian Ocean on either side of India.
4. Solve this crossword Across 1. Abundantly produced by the oceans
OXYGEN - More than half the world's oxygen is produced by marine flora in the oceans, which is why oceans are called the planet's lungs.
4. Solve this crossword Across 3. A large expanse of landmass
CONTINENT
4. Solve this crossword Across 6. A large continent of which India is a part
ASIA
4. Solve this crossword Across 8. A major source of pollution of the oceans
PLASTIC - Several million tonnes of plastic waste are thrown into the oceans every year.
4. Solve this crossword Across 10. The coldest continent
ANTARCTICA
4. Solve this crossword Down 2. The largest island on Earth
GREENLAND
4. Solve this crossword Down 4. A huge destructive wave from the ocean
TSUNAMI
4. Solve this crossword Down 5. The smallest continent
AUSTRALIA
4. Solve this crossword Down 7. The largest body of water on the Earth
PACIFIC - The Pacific Ocean is the largest ocean.
4. Solve this crossword Down 9. A landmass (but not a continent) surrounded by the sea or ocean
ISLAND