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Term 3 Chapter 1 | 4th Science - Green Environment | 4th Science : Term 3 Unit 1 : Green Environment

Chapter: 4th Science : Term 3 Unit 1 : Green Environment

Green Environment

Learning Objectives - After the completion of this unit students will be able to • understand the importance of waste management • understand the role of 3Rs in waste management • learn how to conserve the environment by practising good habits • recognise eco-friendly materials

Unit 1



Learning Objectives

After the completion of this unit students will be able to

• understand the importance of waste management

• understand the role of 3Rs in waste management

• learn how to conserve the environment by practising good habits

• recognise eco-friendly materials



Nature provides us a lot of useful things. But human beings exploit the natural resources and create more trash. These unwanted materials thrown away are called wastes. They can be solid, liquid and gas. They are produced from households, industries, hospitals etc., These unwanted materials pollute our environment.


Waste Management

Sristhika : Madam, I see a lot of waste things in our surrounding. Is there any way we can reduce wasting things?

Teacher: Yes. There are many ways to reduce waste. Reducing the waste is the first and most important step in waste management.

Vimal : What is waste management, Madam?

Teacher: It is the step we take to handle our waste and to make sure our environment does not get dirty and polluted. Waste management deals with both biodegradable and non-biodegradable waste.

Janani: Can you please explain the steps in waste management Madam?

Teacher: Yes, sure. There are four steps in waste management. They are

1. Separation of Waste 

2. Waste collection and transportation

3. Waste recycling and composting

4. Waste disposal

1. Separation of Waste: This is a very important step in waste management. It means to sort or divide the waste into different waste bins. Each bin should have different type of wastes. It is good to separate waste in three different bins. Green for biodegradable waste, Blue for recyclable waste and Red for non-recyclable waste. Non-biodegradable waste can be classified as recyclable and non-recyclable.

Biodegradable, Recyclable, Non-recyclable

2. Waste collection and transportation: Once we separate our waste in our homes and schools, it is important to keep it ready to be picked up by our municipality or corporation. Picking up the waste is called Waste collection. Moving the waste from one place to another is called Transportation.

3. Waste recycling and composting: Biodegradable waste is taken to a place where it can be converted into compost. Compost makes the soil fertile. Non-biodegradable waste that can be turned into something new (recyclable waste) and valuable is taken to recycling factory.

4. Waste disposal: The waste that cannot be recycled (non-recyclable waste) needs to be sent for final disposal. This waste is sent to an open dump or landfill.

Trash box, Recycling, Collection, Sorting, Transportation


Write the waste management process in the correct order.

(Waste disposal, Waste collection and transportation, Waste separation, Waste recycling and composting)

1. Waste separation

2. Waste collection and transportation

3. Waste recycling and composting

4. Waste disposal

Rahul : How can we manage waste at home?

Teacher: There are many things we and our family can do to manage waste at home. Three R‛s help to manage waste.

Gomathi: What are the three R‛s, Madam?

Teacher: The three R‛s stand for REDUCE, REUSE, RECYCLE. We must first reduce, then reuse and finally recycle.


THE 3 R‛s

Reduce is to make or use less materials. This is to make, buy and use things that create less waste. It is the best thing to do first and it is easy to ask yourself – How can I make less waste? Some examples are given below.

1. You can buy a refill pen and change the refill only when the ink is used up.

2. While shopping with your parents, you can carry a cloth bag.

In this way you can avoid buying plastic carry bags.

3. Turn off lights and fans when you leave a room.

4. Close the tap while you are brushing your teeth.


List out four things that you can reduce, reuse and recycle at home or school.

Reuse is using a thing repeatedly for the same or for another purpose. By reusing, we throw away less waste and do not dispose it in a dump. Reuse saves money, energy and time. Here are some examples of how you can reuse materials at home.

1. You can reuse old clothes as a rag to clean your home or even wash your cycle.

2. You can reuse jam and pickle jars to store things.

3. You can donate old clothes that still look good to poor and needy children.

4. You can reuse waste and make something new. E.g. You can reuse a plastic bottle as a pen stand or a bird feeder.

Recycle is to take materials from things you throw away and make new products by using them. Recycling takes energy and time but saves the amount of ‘new‛ resources we need to make things. E.g. water, minerals, wood.

Here are some examples of how certain materials are recycled.

1. Old newspapers, note books and magazines are separated and sold to a scrap dealer. They will be made into new papers.

2. PET bottles are recycled into plastic threads and then used to make sports T-shirts.

3. Old glass bottles and broken glass pieces are melted to make new glass.

4. Broken metal items like tiffin boxes and plates are melted and made into new metal products like toys.


Using old water bottles, make different things such as Bird feeder, Flower vase, Pen holder and Wall hanging as shown below.


Conserve our Environment

Rahul : What is meant by conservation of environment, Madam?

Teacher: Conservation of environment means to protect all things found in nature. It means that we have to use our Earth‛s natural resources (like water, soil, minerals, wildlife and forests) carefully.

Vimal : How can I conserve the environment?

Teacher : Everyone can conserve the environment by following good waste management habits.

What is the first ‘R‛ in the three R‛s?

Kanimozhi : Reduce.

Teacher : Correct! We should first try to reduce the waste we make. Thus, we can easily conserve the environment. We can also separate our waste at home to keep our place litter free and clean.


Waste Separation

Waste at home should be separated into biodegradable, recyclable and non-recyclable waste. Waste like left over food, vegetable waste which are broken down naturally should be collected in a separate litter box. Materials which cannot be decomposed should be placed in separate dustbin. Paper waste, glass waste and aluminium waste which can be recycled into new useful products should be kept in separate box.

Do you Know?

Glass containers for food and beverages are 100% recyclable and can be recycled endlessly without loss in quality or purity.


Study the images below and write down three items you have at home in each category of waste.

Biodegradable | Recyclable items | Non-recyclable items

1. Biodegradable: Fruits, Vegetables, Seeds, Nuts

2. Recyclable: Paper, plastics, glass, metal

3. Non-recyclable: Medical waste, CFL lights, Plastic bags, Polystyrene

Sristhika : I have heard the news that plastic is harmful to our environment. Is it true Mam?

Teacher : Plastic itself is not bad but we are using too much of it. Over use of plastic causes pollution. Plastics that are used only one time causes pollution. It is good to avoid or reduce one-time usable plastics. The best way to start is to ask yourself this question. Is this plastic item going to be used one time or many times? If you can use it only once, then try to avoid buying such plastic items.


Plastics in Tamil Nadu

Tamil Nadu is leading the way in India by banning some one-time use plastic items. List of items banned in Tamil Nadu are given below.

Animals eat plastic bags by accident and their food passage is choked.

Plastic plates stay in the environment for over 1000 years.

Water pouches litter the land and are difficult to recycle.

Plastic straws are difficult to recycle and end up polluting the ocean.

Chemicals from plastic sheets leak into food.

Ekalaivan : What are the things that can be used instead of plastic, Madam?

Teacher : We can use things that are harmless for the environment. These are called environment friendly or eco-friendly materials, and can be either biodegradable or reusable.


Environment friendly materials

Things that can be decomposed or broken down by microorganisms are biodegradable. They can return to the soil and enrich the soil. Materials which are beneficial to the environment and do not cause harm are called eco-friendly materials.

For example, banana leaves are used as plates. They are fully biodegradable and do not contain chemicals like thermocol plastic or coated paper plates.

Bamboo is used to make many things such as bags, dustbins and even toothbrushes.

Eco-friendly Activities:

• Reduce your paper use by writing on both sides of every sheet.

• Stop using plastic straws.

• Use reusable bag.

• Give up chewing gum.

• Buy stainless steel bottles instead of plastic water bottles.

• Reuse containers for storing left overs.

Do you Know?

The first fully synthetic plastic was invented by Leo Baekeland in 1907


Form small groups and start collecting plastic litter from school grounds or from the local area around your house.

Teacher : Some environment friendly materials are not biodegradable but very strong and can be used for many years. Reuse is the second R in three R‛s. By reusing something again and again, we reduce waste and conserve the environment.

Rahul : Can you please give us some examples?

Teacher : Yes, sure.

Stainless steel water bottle and snack box are some examples of eco-friendly materials. Stainless steel does not leak chemicals into your food or water. So it is safer than plastic. These can be reused for a longer period of time.


Write any five non-recyclable items that you use or have seen in shop.

Answer: 1 .Plastic carry bags 2. Straw 3. Plastic plates 4. Plastic sheets 5. Water pouches

Litter Free Environment

Litter in our environment is unsightly and spoils our experience of nature. It is also dangerous to animals that ingest it. Cleaning up loose waste is one of the best ways to keep our community and the environment green. By removing litter from environment, we are ensuring that it does not end up in our oceans.

National Green Corps (NGC)

It is a national programme initiated by the Government of India. The motto of NGC is “Where there is Green, there is Prosperity”

It involves NGC school students in protecting and promoting the conservation of natural resources. They participate in activities like biodiversity conservation and waste management.

Make sure you put litter in a bag or in a dustbin.

When others pass you as you pick up litter, smile and say hello. It shows pride in community and encourages others to do their part

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