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Chapter: 3rd Science : Term 3 Unit 1 : Our Environment

Our Environment

At the end of the lesson the students will be able to * differentiate biotic and abiotic factors * understand the interaction between biotic and abiotic factors * understand balanced ecosystem * understand the importance of planting trees

Unit 1

Our Environment


Learning Objectives

At the end of the lesson the students will be able to

* differentiate biotic and abiotic factors

* understand the interaction between biotic and abiotic factors

* understand balanced ecosystem

* understand the importance of planting trees


I. Environment – Introduction


(Yazhini and her friends are going to school with her father)

Yazhini : Hey! Look at the parrots! Where are they going, daddy?

Father : They are flying towards the pond. Now, they will settle on the trees.

Fathima : Uncle! Uncle! Can you please take us there?

Stephen : Yes uncle. Shall we go and have a look at them?

Father : Oh! Yes!

(They are walking towards the pond)

Yazhini : We should be quiet while walking as, there are not only parrots on the trees but also ant, spider, squirrel, myna and monkey.

Fathima : Oh! Oh! Look at the fish and frog in the pond. I can see a turtle too.

Father : Yes! See how they live in the same place depending on one another.

Stephen : See there, goat and cow are grazing near the pond.

Father : Children, we are getting late. We shall go to school.

Children : Yes uncle. Thank you very much for showing us this beautiful place.

Let Us Try

1. Write the names of the animals that you see in the previous page picture.

Cow Buffalo Goat

Rabit Monkey Turtle

2. Classify the following into natural things and man-made things.

(Dam, river, coconut tree, building, jasmine flower, hill, cloud, silver vessel, cell phone, temple, cake, air, sun, ship, water, pencil, book, doll, football, sunflower, crocodile, aeroplane)

Natural things: River, hill, cloud, air, sun, water, coconut tree, jasmine flower, sun flower, crocodile

Man-made things: Dam, building, silver vessel, cell phone, temple, cake, ship, pencil, book, doll, foot ball, aeroplane

Let Us Enjoy

Shall we mimic like the animals?

Crow, Cuckoo, Elephant, Parrot, Donkey, Cow, Goat, Dog

Let Us Connect

Match the following sources with their products and uses.

II. Environmental Factors


Our environment consists of everything around us. It has living and non-living things. We are surrounded by living things such as plants and animals and non-living things such as water bodies, sunlight, air and land.

The living and non-living things in our environment interact with one another. Our environment is a wonderful gift to us given by the nature.

More to know

Environmentalist - A person who protects the environment.

As an environmentalist, you can volunteer to protect plants and animals.

Our environment has two main factors:

(i) Biotic factors

(ii) Abiotic factors

Biotic Factors

Living organisms in our environment are called biotic factors. E.g., Lion, Plantain, Dove, Human beings etc.

Abiotic Factors

Non-living things in our environment are called abiotic factors. E.g., Air, Soil, Water, Sunlight, Temperature etc.

Difference between biotic and abiotic factors

Biotic Factors (Living things)

They can breathe and grow

They need food to live

They can feel

They give birth to young ones

Abiotic Factors (Non-living things)

They cannot breathe and grow

They do not need food to live

They cannot feel

They do not give birth to young ones

Do you know

Plants cannot move around like animals. But they grow and their shoots show movements towards the sun. So, the plants are also biotic factor.

More to know

Amoeba is an unicellular organism. It has the ability to alter its shape. It was discovered in 1755.

Let Us Try

1. Classify the following as Biotic / Abiotic factors.

2. Think and Answer

a. A swing goes to and fro. Is it living or non-living?

Answer: non-living

b. We get wood from trees which are the living things. A chair is made from wood. Is the chair a living thing or a non-living thing?

Answer: non-living thing

Try to Answer

Look at the picture and answer the question.

Which of the non-living things can float?

a. Iron rod

b. Stone

c. Air filled ball

d. Coin

Answer: c. Air filled ball

Let Us Try

The following statements describe some of the characteristics of living things. Identify and write the characteristic features using the given hints.

(Characteristics Hints: Move, Breathe, Feel, Needs Food, Grow, Reproduce)

Let Us Play

Divide the class into two groups and ask the first group to write any five biotic factors and the second group to write any five abiotic factors seen around the school.


III. Interaction between biotic and abiotic factors


All biotic factors depend upon abiotic factors for their living. Biotic and abiotic factors are linked to each other by the flow of energy through food. Plants are the most important among all the living organisms. Because they only can make food from abiotic factors like air, soil, water and sunlight.

A few examples for interaction between biotic and abiotic factors are given below.

From the above picture we understand that plants need water, soil, air and sunlight to live.

Write the needs of the following.

1. Birds : Air, Water, Sunlight, Insects, Trees

2. Insects : Soil, Air, Plants, Small creatures

3. Human beings: Air, Water, Plants, Sunlight, Animals.

More to know

Ecology is the science that deals with the relationship between living things and their environment.

Let Us Discuss

1. There is a large banyan tree in a park. Monkeys and birds have made the tree their home. Humans too spend time under the tree. Discuss with your friends, how the tree, monkeys, birds and humans are interdependent.

Birds and monkeys feed on the fruit. Birds build their nests in the tree. The tree gives shade to human beings when the day is hot. The wood of the tree is useful to human beings. The droppings of the birds are a manure to the tree. Birds play a vital role in dispersal of seeds. Thus the tree, monkeys, birds and human beings are interdependent.

2. Why is plant the most important living thing?

Because they make food from abiotic factors.

3. Discuss in a group and create an interlink of living and non-living factors.

Biotic and abiotic factors are linked to each other by the flow of energy through food.

Let Us Try

1. Write the abiotic factors needed for the following biotic factors to survive.

(Air, Water, Sunlight, Soil, Land, Wheat, Fruits, Grass, Hen)

a. Animals: Air, Water, Sunlight, Land, Grass

b. Plants: Air, Water, Sunlight, Soil

c. Human beings: Air, Water, Sunlight, Land, Wheat, Fruits, Hen

2. An animal that

a. flies in the air is: aerial

b. lives in water is: aquatic animals

c. moves on the ground is: Terrestrial animals

d. eats only plants is: Herbivores


IV. Balanced Ecosystem


Imagine an environment where there are only plants, deer and lions.

* What will happen to the deer if we remove all the lions?

* What will happen to the plants if there are no lions to eat the deer?

* If all the plants are eaten, what will happen to the deer?

It is important for the food chain to exist in any ecosystem to make sure that the energy flows between the biotic and abiotic factors. A balanced ecosystem supports animals, plants and microorganisms to grow in their environment. An ecosystem is balanced, when the biotic and abiotic factors are able to cycle the energy and food as per their need.

The biotic factors in an ecosystem includes producers, consumers and decomposers.

1. Producers

The living things that can prepare their own food are called producers. Green plants are the producers. They make their own food by the process of photosynthesis. Hence, they are called primary producers. Humans and animals depend on plants for their food.

More to know

A few plants do not produce their food and they depend on other plants. They are called parasitic plants. E.g., Cuscuta

2. Consumers

The living things that eat the food prepared by the producers are called consumers. Most of the living things depend directly or indirectly on producers for their food. Consumers can be divided into three types based on their food as herbivores (plant eating animal), carnivores (flesh eating animal), omnivores (both plant and flesh eating animal).

3. Decomposers

Organisms that feed on the wastes, dead plants and animals are called decomposers. They return the nutrients to the soil.

E.g., Bacteria, Fungi.

Let Us Try

Classify the following biotic factors.

(Tulsi, Fungi, Mango tree, Rabbit, Eagle, Cat, Dog, Cucumber plant, Human, Grass, Crocodile, Crow, Bacteria)

Producers : Tulsi, Mango tree, Cucumber plant, Grass

Consumers : Rabbit, Eagle, Cat, Dog, Human, Crocodile, Crow

Decomposers : Fungi. Bacteria

Let Us Discuss

1. Let us discuss and write.

Plants and human beings are living things. Why do human beings depend on plants?

Human beings obtain food from plants and oxygen for respiration. So they depend on plants.

2. Divide the students into three groups and give them some pictures of living things. Ask them to classify the pictures based on their food habits.

3. Take your students outside the classroom or to a park. Ask them to note down the producers and consumers they could identify there.

Let Us Try

The names of several natural resources are hidden in the box below. Find as many as possible. Some words are repeated.

Let us Connect

Link the animals as herbivores, carnivores and omnivores.


V. Plant Sapling


A young plant with a thin stem is known as a sapling. Survival of living things is impossible without plants. Planting and taking care of plants lead to a good environment.

Benefits of plants

* Provide oxygen for breathing

* Provide food and shelter to living things

* Absorb harmful gases and smoke from the surroundings

* Help in bringing rainfall

* Give wood for making furniture

* Offer a good environment to live

Do you know


Van Mahotsav means, “Festival of forests”. It is an annual tree planting movement. This movement began in India in July 1950.This festival is organised during the first week of July every year.

To create awareness among the people, we can give saplings during celebrations, family functions and national festivals. We can also plant saplings on our birthday.

More to know

Some important initiatives to protect our environment.

The Chipko Movement - 1970

The Environment Protection Act – 1986

National Green Tribunal – 2010

Appiko Movement – 1983

Let Us Do

A. Write any two uses of trees.

1. Help in bringing rainfall

2. Provide oxygen

B. Conduct an awareness campaign on ‘Save Our Environment’.

C. Plant saplings in your school campus.

D. Preparation of seed ball

Take some clay, humus, add water and mix well. After mixing, place the available seeds inside them and make a seed ball. Then dry and keep it safe. Distribute the seed balls to public on special occasions of your school.

E. Write some slogans on ‘Save Plants’ and paste them on the tree in your school campus/road sides. (E.g., Take care of the Earth and it will take care of you. It’s not yours, nor mine, it’s ours)

1. Trees look fair, they clean the air.

2. Forests are our wealth. They preserve our health.

The nature of our future depends on the future of our nature.

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