What did you eat at home

today? Find out what your

friend ate today. Did you eat

the same kind of food yesterday and

today? We all eat different kinds of food

at different times, isn’t it?

1.1 FOOD VARIETY

Activity 1

Ask your friends in the school about the

items they would be eating during a day.

See if you can also get this information

from friends staying in different states

of India. List all the items in your

notebook as given in Table 1.1, for as

many friends as possible.

Table 1.1 What do we eat?

Nam e of the

student/friend

Food it em s

eat e n in a day

There seems to be so much variety

in the food that we eat (Fig 1.1). What

are these food items made of?

Think about rice

cooked at home. We take

raw rice and boil it in

water. Just two materials

or ingredients are

needed to prepare a dish of boiled rice.

On the other hand, some food items

are made with many ingredients. To

prepare vegetable curry, we need

different kinds of vegetables, salt, spices,

oil and so on.

Activity 2

Choose some of the items you listed in

Table 1.1 and try to find out what

ingredients are used to prepare these,

by discussing with your friends and

elders at home. List them in Table 1.2.

Some examples are given here. Add

some more items to this list.

Table 1.2 Food items and their

ingredients

Food Item Ingredients

Roti/chapati Atta, water

Dal Pulses, water, salt, oil/

ghee, spices

Food:

Where Does it Come From?

Fig. 1.1 Different food items

SCIENCE2

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

Activity 3

Let us take the food items listed earlier

and try to find out where they come from

— the ingredients and their sources.

Some examples are shown in Table 1.3.

Fill in the blanks in Table 1.3 and add

more examples to this list.

What do we find? Do we find some ingredients common

for different food items? Discuss in class.

So, where do these ingredients come from?

1.2 FOOD MATERIALS AND SOURCES

It may be easy for us to guess the sources of some of the

ingredients that we listed in Table 1.2. Fruits and

vegetables, for instance (Fig. 1.2a). Where do they come

from? Plants, of course! What are the sources of rice or

wheat? You may have seen paddy or wheat fields with rows

and rows of plants, which give us these grains (Fig. 1.3).

And then, there are food items like milk, eggs and meat,

which come from animals (Fig. 1.2b).

Table 1.3 Ingredients used to

prepare food items and

their sources

Food Item Ingredients Sources

Idli Rice Plant

Urad dal

Salt

Water

Chicken

curry Chicken Animal

Spices

Oil/ghee Plants/

Animals

Water

Kheer Milk Animal

Rice Plant

Sugar

(a) Plant sources

(b) Animal sources

Fig. 1.2 Sources of

food ingredients

Fig. 1.3 Source of food grains

(a) Paddy field (b) Wheat grains transported

(a)

(b)

FOOD: WHERE DOES IT COME FROM?3

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

flowers dipped in rice paste and fried?

Try it!

Some plants have two or more edible

(eatable) parts. Seeds of mustard plants

give us oil and the leaves are

used as a vegetable. Can you think of

the different parts of a banana plant that

are used as food? Think of more

examples where two or more parts of a

single plant are used as food.

What do we conclude from Activity

3? Plants are the sources of food

ingredients like grains, cereals,

vegetables and fruits. Animals provide

us with milk, meat products and eggs.

Cows, goats and buffaloes are some

common animals which give us milk.

Milk and milk products like butter,

cream, cheese and curd are used all over

the world. Can you name some other

animals which give us milk?

1.3 PLANT PARTS AND ANIMAL

PRODUCTS AS FOOD

Plants are one source of our food. Which

parts of a plant?

We eat many leafy vegetables. We eat

fruits of some plants. Sometimes roots,

sometimes stems and even flowers

(Fig 1.4). Have you ever eaten pumpkin

Paheli wants to know if any of our

food comes from sources other

than plants and animals.

Table 1.4 Plant parts as food

Food item with plant

as the major source

Ingredients/source Plant part which gives

us the ingredient

1. Brinjal curry Brinjal Fruit

Chilli as spice (any other) Fruit

Oil from groundnut, mustard,

soybean, any other plant Seed

Fig. 1.4 Different edible parts of plants

SCIENCE4

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

Fig. 1.5 Whole moong and its sprouts

Activity 4

From all the food items you have listed

in Table 1.3, choose those items whose

ingredients are obtained from plants.

Which part of a plant? Identify these

and list the food items and plant parts

as shown in Table 1.4.

Activity 5

Take some dry seeds of moong or chana.

Put a small quantity of seeds in a

container filled with water and leave this

aside for a day. Next day, drain the water

completely and leave the seeds in the

vessel. Wrap them with a piece of wet

cloth and set aside. The following day,

do you observe any changes in the seeds?

covered with a wet cloth. The next day,

see if the seeds have sprouted.

After washing these sprouted seeds,

you can eat them. They can also be

boiled. Add some spices and get a tasty

snack to eat.

Do you know where honey comes

from, or how it is produced? Have you

seen a beehive where so many bees keep

buzzing about? Bees collect nectar

(sweet juices) from flowers, convert it

Do not try to taste unknown plants

around you to see if they are edible!

Some plants could be poisonous.

A small white structure may have grown

out of the seeds. If so, the seeds have

sprouted (Fig. 1.5 and 1.6). If not, wash

the seeds in water, drain the water and

leave them aside for another day,

Fig. 1.6 Chana (gram) and its sprouts

Fig. 1.7 Beehive

into honey and store it in their hive

(Fig. 1.7). Flowers and their nectar may

be available only for a part of the year.

So, bees store this nectar for their use

all through the year. When we find such

a beehive, we collect the food stored by

the bees as honey.

1.5 WHAT DO ANIMALS EAT?

Do you have cattle or a pet that you take

care of? A dog, cat, buffalo or a goat?

FOOD: WHERE DOES IT COME FROM?5

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

You will then surely be aware of the food,

the animal eats. What about other

animals? Have you ever observed what

a squirrel (Fig 1.8), pigeon, lizard or a

small insect may be eating as their food?

Activity 6

Several animals are listed in Table 1.5.

For some of them, the type of food they

eat is also given. Fill in the blanks in

the table.

Activity 7

Have a look again at Table 1.5 and group

the animals entered here as follows.

Place animals which eat only plants or

plant products in Group 1. These are

called herbivores. There are some

animals which eat other animals.

Place these in Group 2. These animals

are called carnivores. Do you find

some animals which eat both plants

and animals? Place them in Group 3.

These are called omnivores. Prepare

a table as in Table 1.6 and enter

these separately in the three columns,

as shown.

Paheli wants to know where you

would place human beings,

while filling Table 1.6.

We know that there are many

amongst us, who do not get sufficient

Table 1.5 Animals and their Food

Name of the

animal

Food the

animal eats

Buffalo Grass, oilcake,

hay, grains

Cat Small animals,

birds, milk

Rat

Lion

Tiger

Spider

House lizard

Cow

Human beings

Butterfly

Crow

Others

Table 1.6

Herbivores Carnivores Omnivores

Cow Lion Dog

Fig. 1.8 Squirrel eating nuts

SCIENCE6

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

nThere is a lot of variation in the food eaten in different regions of India.

nThe main sources of our food are plants and animals.

nAnimals which eat only plants are called herbivores.

nAnimals which eat only animals are called carnivores.

nAnimals which eat both plants as well as other animals are called

omnivores.

food. We need to find ways by which

more food can be produced in the

country. That will not be enough; we

will need to find ways to ensure that

this food is made easily available to each

one of us.

stneidergnI

elbidE

ratceN

sdeesdetuorpS

erovibreH

erovinraC

erovinmO

1. Do you find that all living beings need the same kind of food?

2. Name five plants and their parts that we eat.

3. Match the items given in Column A with that in Column B

AnmuloC BnmuloC

,druc,kliM reenap ,eehg , slaminarehtotae

torrac,rewolfiluac,hcanipS stcudorptnalpdnastnalptae

sregitdnasnoiL selbategevera

serovibreH stcudorplaminallaera

FOOD: WHERE DOES IT COME FROM?7

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

SUGGESTED PROJECTS AND ACTIVITIES

1. You must have seen a garden lizard around your home. Next time when-

ever you see it, observe carefully and find out what it takes for food. Is the

food different from that of a house lizard?

2. Make a list (with pictures, when possible) of food items generally taken by

people of different regions of India. Place these on a large outline map of

India to display in your classroom.

3. Find out the names of plants that grow in water and which are eaten

as food.

4. In Chapter 10, you will find out ways of measuring length of curved lines.

In your mathematics classes you will learn to prepare bar graphs. After

you learn these, try the following interesting project. Prepare some sprouts

of moong as discussed in the chapter. Wash them in water everyday and

drain all the water. Let them grow for a week until the whole of the seeds

grow into young plants. Measure the lengths of the sprouts everyday using

a string. Take care that they do not break. Prepare a bar graph of the

number of sprouts having lengths in different ranges.

THINGS TO THINK ABOUT

1. Does everyone around you get enough food to eat? If not, why?

2. What are the ways we can think of to avoid wastage of food?

4. Fill up the blanks with the words given:

herbivore, plant, milk, sugarcane, carnivore

(a) Tiger is a ____________________ because it eats only meat.

(b) Deer eats only plant products and so, is called ______________.

(d) The ________________ that we drink, which comes from cows, buffaloes and

goats is an animal product.

(e) We get sugar from ___________________.

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

SCIENCE

In Chapter 1, we made lists of the

food items that we eat. We also

identified food items eaten in

different parts of India and marked

these on its map.

A meal could consist of chapati, dal

and brinjal curry. Another may be rice,

sambar and a vegetable preparation of

lady’s finger (bhindi). Yet another meal

could be appam, fish curry and

vegetables.

curd, butter milk and pickles. Some

examples of meals from different regions

are given in Table 2.1. Select food items

you depicted on the map in Chapter 1.

Add some more meals to this list and

enter these in Table 2.1.

Sometimes, we may not really have

all this variety in our meals. If we are

travelling, we may eat whatever is

available on the way. It may not be

possible for some of us, to eat such a

variety of items, most of the time.

There must be some reason though,

why meals usually consist of such a

distribution. Do you think that our body

needs different kinds of food for some

special purpose?

2.1 WHAT DO DIFFERENT FOOD

ITEMS CONTAIN?

We know that each dish is usually made

up of one or more ingredients, which

we get from plants or animals. These

Components of Food

Table 2.1 Some common meals of different regions/states

Region/

State Item of grain Item of

dal/meat Vegetables Others

Punjab Makki (corn) roti Rajma

(Kidney beans)

Sarson saag

(Mustard leaf curry) Curd, ghee

Andhra

Pradesh Rice Tuar dal and

rasam (charu)Kunduru (dondakai)Buttermilk, ghee,

pickle (aavakai)

Activity 1

Our meals usually have at least one item

made of some kind of grain. Other items

could be a dal or a dish of meat and

vegetables. It may also include items like

COMPONENTS OF FOOD

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

Fig. 2.1 Testing for starch

ingredients contain some components

that are needed by our body. These

components are called nutrients. The

major nutrients in our food are named

carbohydrates, proteins, fats, vitamins

and minerals. In addition, food contains

dietary fibres and water which are also

needed by our body.

Do all foods contain all these

nutrients? With some simple methods

we can test whether cooked food or a

raw ingredient contains one or more of

these nutrients. The tests for presence

of carbohydrates, proteins and fats

are simpler to do as compared to the

tests for other nutrients. Let us do these

tests and record all our observations

in Table 2.2.

For carrying out these tests, you will

need solutions of iodine, copper

sulphate and caustic soda. You will also

need a few test tubes and a dropper.

Try these tests on cooked food items

as well as raw materials. Table 2.2 shows

you a way to record the observations

from these tests. Some food items are

given in this table. You can conduct the

tests either with these or any other

available food items. Do these tests

carefully and do not try to eat or taste

any chemicals.

If the required solutions are not

available in readymade form, your

teacher can prepare them as given in

the box.

Let us begin by testing different

food items to see if they contain

carbohydrates. There are many

types of carbohydrates. The main

carbohydrates found in our food are in

the form of starch and sugars. We can

easily test if a food item contains starch.

Activity 2

Test for Starch

Take a small quantity of a food item or

a raw ingredient. Put 2-3 drops of dilute

iodine solution on it (Fig. 2.1). Observe

if there is any change in the colour of

the food item. Did it turn blue-black?

A dilute solution of iodine can be

prepared by adding a few drops of

tincture iodine to a test tube half filled

with water.

Copper sulphate solution can be

prepared by dissolving 2 gram (g) of

copper sulphate in 100 millilitre (mL)

of water.

10 g of caustic soda dissolved in

100 mL of water makes the required

solution of caustic soda.

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

SCIENCE

A blue-black colour indicates that it

contains starch.

Repeat this test with other food items

to find out which of these contain starch.

Enter all your observations in Table 2.2.

Test for Protein

Take a small quantity of a food item for

Fig. 2.2 Testing for protein

Table 2.2 Nutrients present in some

food items

Food item Starch

(present)

Protein

(present)

Fat

(present)

Raw potato Yes

Milk Yes

Groundnut Yes

Uncooked

powdered

rice

Cooked rice

Dry coconut

Uncooked

tuar dal

(powdered)

Cooked dal

A slice of any

vegetable

A slice of any

fruit

Boiled egg

(white

portion)

testing. If the food you want to

test is a solid, you first need to

make a paste of it or powder it.

Grind or mash a small quantity

of the food item. Put some of this

in a clean test tube, add 10 drops

of water to it and shake the

test tube.

Now, using a dropper, add

two drops of solution of copper

sulphate and ten drops of

solution of caustic soda to the

test tube (Fig. 2.2). Shake well and let

the test tube stand for a few minutes.

What do you see? Did the contents of

the test tube turn violet? A violet colour

indicates presence of proteins in the

food item.

Now, you can repeat this test on other

food items.

COMPONENTS OF FOOD

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

fats and carbohydrates are also

called ‘energy giving foods’ (Fig. 2.3

and Fig. 2.4).

Proteins are needed for the growth

and repair of our body. Foods

Test for Fats

Take a small quantity of a food item.

Wrap it in a piece of paper and crush it.

Take care that the paper does not tear.

Now, straighten the paper and observe

it carefully. Does it have an oily patch?

Hold the paper against light. Are you

able to see the light faintly, through

this patch?

An oily patch on paper shows that

the food item contains fat. The food

items may sometimes contain a little

water. Therefore, after you have rubbed

an item on paper, let the paper dry for a

while. If there were any water that may

have come from food, it would dry up

after some time. If no oily patch shows

up after this, the food item does not

contain any fat.

What do these tests show? Are fats,

proteins and starch present in all the

food items that you tested? Does a food

item contain more than one nutrient?

Do you find any food item that does not

contain any of these nutrients?

We tested food items for three

nutrients — carbohydrates, proteins

and fats. There are also other nutrients

l i k e vitamins and minerals that are

present in different food items. Why do

we need all these nutrients?

2.2 WHAT DO VARIOUS NUTRIENTS DO

FOR OUR BODY?

Carbohydrates mainly provide energy

to our body. Fats also give us energy.

In fact, fats give much more energy

as compared to the same amount of

carbohydrates. Foods containing

Fig. 2.3 Some sources of carbohydrates

Fig. 2.4 Some sources of fats: (a) plant sources

and (b) animal sources

(a)

(b)

Sugarcane

Sweet potato

Wheat

Rice

Bajra

Melon

Mango

Potato

Maize

Papaya

Groundnuts

Nuts

Til

Meat

Fish

Eggs

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

SCIENCE

proteins are often called ‘body building

foods’ (Fig 2.5).

Vitamins help in protecting our body

against diseases. Vitamins also help in

keeping our eyes, bones, teeth and gums

healthy.

Vitamins are of different kinds

known by different names. Some of these

are Vitamin A, Vitamin C, Vitamin D,

Vitamin E and K. There is also a group

of vitamins called Vitamin B-complex.

Our body needs all types of vitamins in

small quantities. Vitamin A keeps our

skin and eyes healthy. Vitamin C helps

body to fight against many diseases.

Vitamin D helps our body to use

calcium for bones and teeth. Foods that

are rich in different vitamins are shown

in Fig. 2.6 to Fig. 2.9.

Minerals are needed by our body in

small amounts. Each one is essential

Fig. 2.5 Some sources of proteins: (a) plant

sources and (b) animal sources

Meat

Eggs

Fish

Peas

Gram Moong Tuar dal

Beans

Soyabeans

(a)

(b)

Paneer

Fig. 2.6 Some sources of Vitamin A

Liver

Guava

Lemon

Amla

Fig. 2.7 Some sources of Vitamin B

Fig. 2.8 Some sources of Vitamin C

Fig. 2.9 Some sources of Vitamin D

Tomato

Orange

Papaya

Carrot

Mango

Wheat Rice

Green

Chilli

Fish

Egg

Liver

COMPONENTS OF FOOD

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

for proper growth of body and to

maintain good health. Some sources of

different minerals are shown in Fig. 2.10.

Most food items, usually, have more

than one nutrient. You may have noticed

this, while recording your observations

in Table 2.2. However, in a given raw

material, one particular nutrient may

be present in much larger quantity than

in others. For example, rice has more

carbohydrates than other nutrients.

Thus, we say that rice is a “carbohydrate

rich” source of food.

Besides these nutrients, our body

needs dietary fibres and water. Dietary

fibres are also known as roughage.

Roughage is mainly provided by plant

products in our foods. Whole grains and

pulses, potatoes, fresh fruits and

vegetables are main sources of roughage.

Roughage does not provide any nutrient

to our body, but is an essential

component of our food and adds to its

bulk. This helps our body get rid of

undigested food.

Our body also

prepares Vitamin D in the

presence of sunlight. Nowadays,

insufficient exposure to sunlight is

causing Vitamin D deficiency in

many people.

Fig. 2.10 Sources of some minerals

Some sources

of calcium

Some sources

of iron

Some sources of

phosphorous

Some sources of

iodine

Ginger

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

SCIENCE

think that, what we need for a balanced

diet would depend on the amount of

physical work that we do?

Prepare a chart of whatever you eat

over a period of a week. Check whether

all the nutrients mentioned are present

in one or the other food items being

eaten within a day or so.

Pulses, groundnut, soyabean,

sprouted seeds (moong and Bengal

gram), fermented foods (South Indian

foods such as idlis), a combination of

flours (missi roti, thepla made from

cereals and pulses), banana, spinach,

sattu, jaggery, available vegetables and

other such foods provide many

nutrients. Therefore, one can eat a

balanced diet without expensive food

materials.

Eating the right kind of food is not

enough. It should also be cooked

Water helps our body to absorb

nutrients from food. It also helps in

throwing out some wastes from body as

urine and sweat. Normally, we get most

of the water that our body needs from

the liquids we drink — such as water,

milk and tea. In addition, we add water

to most cooked foods. Let’s see if there

is any other source which provides water

to our body.

Activity 3

Take a tomato or a fruit like lemon. Cut

it into small pieces. Do your hands get

wet while doing so?

Carefully observe whenever

vegetables and fruits are being cut,

peeled, grated or mashed at your

home. Do you find any fresh vegetables

or fruits that do not contain some

amount of water?

We see that many food materials

themselves contain water. To some

extent, our body needs are met by this

water. Apart from this, we also add water

while cooking many food items.

2.3 BALANCED DIET

The food we normally eat in a day is our

diet. For growth and maintenance of

good health, our diet should have all

the nutrients that our body needs, in

right quantities. Not too much of one

and not too little of the other. The diet

should also contain a good amount of

roughage and water. Such a diet is called

a balanced diet.

Do you think that people of all ages

need the same type of diet? Do you also

Paheli wonders whether animal

food also consists of these

different components and do

they also need a balanced diet?

properly so that its nutrients are not

lost. Are you aware that some nutrients

get lost in the process of cooking and

preparations?

If the vegetables and fruits are

washed after cutting or peeling them, it

COMPONENTS OF FOOD

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

may result in the loss of some vitamins.

The skins of many vegetables and fruits

contain vitamins and minerals.

Similarly, repeated washing of rice and

pulses may remove some vitamins and

minerals present in them.

We all know that cooking improves

the taste of food and makes it easier to

digest. At the same time, cooking also

results in the loss of certain nutrients.

Many useful proteins and considerable

amounts of minerals are lost if excess

water is used during cooking and is

then thrown away.

Vitamin C gets easily destroyed by

heat during cooking. Would it not be

sensible to include some fruits and raw

vegetables in our diet?

Boojho thought that fats would be

the best foods to eat, all the time. A katori

(bowl) of fat will give much more energy

than a katori of carbohydrate rich food,

isn’t it? So, he ate nothing but food rich

in fats — fried food like samosa and poori

(snacks), malai, rabdi and peda (sweets).

Do you think he was right? No, of

course not! It can be very harmful for

us to eat too much of fat rich foods and

we may end up suffering from a

condition called obesity.

2.4 DEFICIENCY DISEASES

A person may be getting enough food to

eat, but sometimes the food may not

contain a particular nutrient. If this

continues over a long period of time, the

person may suffer from its deficiency.

Deficiency of one or more nutrients can

cause diseases or disorders in our body.

Diseases that occur due to lack of

nutrients over a long period are called

deficiency diseases.

If a person does not get enough

proteins in his/her food for a long time,

he/she is likely to have stunted growth,

swelling of face, discolouration of hair,

skin diseases and diarrhoea.

If the diet is deficient in both

carbohydrates and proteins for a long

period of time, the growth may stop

completely. Such a person becomes very

lean and thin and so weak that he/she

may not even be able to move.

Deficiency of different vitamins and

minerals may also result in certain

diseases or disorders. Some of these are

mentioned in Table 2.3.

All deficiency diseases can be

prevented by taking a balanced diet.

In this chapter, we asked ourselves

the reason why widely varying food from

different regions had a common

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

SCIENCE

Table 2.3 – Some diseases/disorders caused by

deficiency of vitamins and minerals

/nimatiV

lareniM

ycneicifeD

/esaesid

redrosid

smotpmyS

AnimatiV noisivfossoL

fossol,noisivrooP

ssenkradninoisiv

semitemos,)thgin(

noisivfossoletelpmoc

nimatiV

1B irebireB

dnaselcsumkae

otygreneelttilyrev

krow

CnimatiV yvrucS

,smuggnideel

regnolekatsdnuow

laehotemit

DnimatiV stekciR

tfosemocebseno

tnebdna

muiclaC htootdnaenoB

yaced

htoot,senobkaeW

yaced

enidoI retioG

kcenehtnisdnal

,nellowsraeppa

niytilibasidlatnem

nerdlihc

norI aimeanA

ssenkae

teiddecnalaB

irebireB

setardyhobraC

ygrenE

staF

slareniM

stneirtuN

snietorP

egahguoR

yvrucS

hcratS

snimatiV

nThe major nutrients in our food are carbohydrates, proteins, fats, vitamins

and minerals. In addition, food also contains dietary fibres and water.

nCarbohydrates and fats mainly provide energy to our body.

nProteins and minerals are needed for the growth and the maintenance

of our body.

nVitamins help in protecting our body against diseases.

nBalanced diet provides all the nutrients that our body needs, in right

quantities, along with adequate amount of roughage and water.

nDeficiency of one or more nutrients in our food for a long time may cause

certain diseases or disorders.

distribution. This distribution, we find, ensures that

our meals have a balance of the different nutrients

needed by the body.

COMPONENTS OF FOOD

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

SUGGESTED PROJECTS AND ACTIVITIES

1. Prepare a diet chart to provide balance diet to a twelve year old child. The

diet chart should include food items which are not expensive and are com-

monly available in your area.

2. We have learnt that excess intake of fats is harmful for the body. What about

other nutrients? Would it be harmful for the body to take too much of proteins

or vitamins in the diet? Read about diet related problems to find answers to

these questions and have a class discussion on this topic.

3. Test the food usually eaten by cattle or a pet to find out which nutrients are

present in animal food. Compare results obtained from the whole class to

conclude about balanced diet requirements for different animals.

1. Name the major nutrients in our food.

2. Name the following:

(a) The nutrients which mainly give energy to our body.

(b) The nutrients that are needed for the growth and maintenance of our body.

(d) A mineral that is required for keeping our bones healthy.

3. Name two foods each rich in:

(a) Fats

(b) Starch

(d) Protein

4. Tick (Ö) the statements that are correct.

(a) By eating rice alone, we can fulfill nutritional requirement of our body. ( )

(b) Deficiency diseases can be prevented by eating a balanced diet. ( )

(d) Meat alone is sufficient to provide all nutrients to the body. ( )

5. Fill in the blanks.

(a) ______________ is caused by deficiency of Vitamin D.

(b) Deficiency of ______________ causes a disease known as beri-beri.

(d) Night blindness is caused due to deficiency of ____________ in our food.

18 SCIENCE

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

3Fibre to Fabric

Fig. 3.1 A cloth shop

Fig.3.2 Enlarged view

of a piece of fabric

Paheli and Boojho won the first

prize in a Science Quiz

competition held at their school.

They were very excited and decided to

use the prize money to buy clothes for

their parents. When they saw a large

variety of cloth material, they got

confused (Fig. 3.1). The shopkeeper

explained that some clothes or fabrics

were cotton and some were synthetic.

He also had woollen mufflers and

shawls. There were many silk sarees as

well. Paheli and Boojho felt very excited.

They touched and felt these different

fabrics. Finally, they bought a woollen

muffler and a cotton saree.

After their visit to the cloth shop,

Paheli and Boojho began to notice

various fabrics in their surroundings.

They found that bed sheets, blankets,

curtains, tablecloths, towels and

dusters were made from different kinds

of fabrics. Even their school bags and

the gunny bags were made from

some kind of fabric. They tried to

identify these fabrics as cotton, wool,

silk or synthetic. Can you also identify

some fabrics?

3.1 VARIETY IN FABRICS

Activity 1

Visit a nearby tailoring shop.

Collect cuttings of

fabrics leftover after

stitching. Feel and

touch each piece

of fabric. Now,

try to label some

of the fabrics as

cotton, silk, wool

or synthetic after

asking for help from the tailor.

Do you wonder what these different

fabrics are made of? When you look at

any fabric, it seems a continuous piece.

Now, look at it closely. What do you

notice (Fig. 3.2)?

Activity 2

Select a piece of cotton fabric you

labelled in Activity 1. Now, try to find a

loose thread or yarn at one of the edges

and pull it out (Fig. 3.3). If no loose

19FIBRE TO FABRIC

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

Fig. 3.3 Pulling a thread from a fabric

Fig.3.4 Splitting the yarn into thin strands

Fig. 3.5 Yarn split up into thin strands

yarns are visible, you can gently pull

one out with a pin or a needle.

We find that a fabric is made up of

yarns arranged together. What are these

yarns made of?

3.2 FIBRE

Activity 3

Take out a yarn from a piece of cotton

fabric. Place this piece of yarn on the

table. Now, press one end of the yarn

with your thumb. Scratch the other end

of the yarn along its length with your

nail as shown in Fig. 3.4. Do you find

that at this end, the yarn splits up into

thin strands (Fig. 3.5)?

You might have observed something

similar when you try to thread a

needle. Many a time, the end of the

thread is separated into a few thin

strands. This makes it difficult to pass

the thread through the eye of the

needle. The thin strands of thread that

we see, are made up of still thinner

strands called fibres.

Fabrics are made up of yarns and

yarns are further made up of fibres.

Where do these fibres come from?

The fibres of some fabrics such as

cotton, jute, silk and wool are obtained

from plants and animals. These are

called natural fibres. Cotton and jute

are examples of fibres obtained from

plants. Wool and silk fibres are obtained

from animals. Wool is obtained from the

fleece of sheep or goat. It is also obtained

from the hair of rabbits, yak and

camels. Silk fibre is drawn from the

cocoon of silkworm.

For thousands of years natural fibres

were the only ones available for making

fabrics. In the last hundred years or so,

fibres are also made from chemical

Boojho has seen in the

museums, items like the

one shown here. These

were worn by warriors. He

wants to know if these

are made of some

kinds of fibre.

20 SCIENCE

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

substances, which are not obtained

from plant or animal sources. These are

called synthetic fibres. Some examples

of synthetic fibres are polyester, nylon

and acrylic.

3.3 SOME PLANT FIBRES

Cotton

Have you ever made wicks for oil lamps?

What do you use for making these

wicks? This cotton wool is also used for

filling mattresses, quilts or pillows.

Take some cotton wool, pull it apart

and look at its edges. What do you

observe? The small, thin strands that

you see are made up of cotton fibres.

Where does this cotton wool come

from? It is grown in the fields. Cotton

plants are usually grown at places

having black soil and warm climate. Can

you name some states of our country

where cotton is grown? The fruits of the

cotton plant (cotton bolls) are about the

size of a lemon. After maturing, the bolls

burst open and the seeds covered with

cotton fibres can be seen. Have you ever

Jute

Jute fibre is obtained from the stem of

the jute plant (Fig 3.8). It is cultivated

during the rainy season. In India, jute

is mainly grown in

West Bengal, Bihar

and A ssam. The

jute plant is

normally harvested

when it is at

flowering stage.

The stems of the

harvested plants

are immersed in

water for a few

days. The stems rot

and fibres are

separated by hand.

Fig.3.6 Field of cotton plants

Fig. 3.7 Ginning of cotton

seen a cotton field that is ready for

picking? It looks like a field covered with

snow (Fig.3.6).

From these bolls, cotton is usually

picked by hand. Fibres are then

separated from the seeds by combing.

This process is called ginning of cotton.

Ginning was traditionally done by hand

(Fig.3.7). These days, machines are also

used for ginning.

Fig. 3.8 A jute plant

21FIBRE TO FABRIC

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

Fig. 3.10

A Takli

Fig. 3.11 Charkha

To make fabrics, all these fibres are

first converted into yarns. How is

it done?

3.4 SPINNING COTTON YARN

You can try making cotton yarn yourself.

Activity 4

Hold some cotton wool in one hand.

Pinch some cotton between the

thumb and forefinger of the other hand.

Now, gently start pulling out the cotton,

while continuously twisting the fibres

(Fig. 3.9). A re you able to

make a yarn?

The process of making yarn

from fibres is called spinning.

In this process, fibres from a

mass of cotton wool are drawn

out and twisted. This brings

the fibres together to form

a yarn.

A simple device used

for spinning is a hand

spindle, also called takli

(Fig. 3.10). Another hand

operated device used for

spinning is charkha

(Fig. 3.11). Use of charkha was

popularised by Mahatma

Gandhi as part of the

Independence movement. He

encouraged people to wear

clothes made of homespun yarn termed

as khadi and shun imported cloth made

in the mills of Britain. To popularise and

promote khadi, the Government of India

constituted a body called Khadi and

Village Industries Commission in 1956.

Spinning of yarn on a large scale is

done with the help of spinning

machines. After spinning, yarns are

used for making fabrics.

3.5 YARN TO FABRIC

There are many ways by which fabrics

are made from yarns. The two main

processes are weaving and knitting.

Weaving

In Activity 2, you might have noticed

that a fabric is made up of two sets of

yarns arranged together. The process of

arranging two sets of yarns together to

make a fabric is called weaving. Let us

try to weave some paper strips.

Activity 5

Take two sheets of paper of different

colours. Cut square pieces of length and

width equal to 30 cm from each sheet.

Now, fold both the sheets into half. On

one sheet draw lines as shown in the

Fig. 3.9 Making yarn from cotton

22 SCIENCE

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

Fig. 3.13 Handloom

Fig. 3.12 Weaving with paper strips

(a)

Fig 3.14 Knitting

Fig 3.12 (a) and on the other as shown

in Fig.3.12 (b). Cut both the sheets

along the dotted lines and then unfold.

Weave the strips one by one through the

cuts in the sheet of paper as shown in

Fig.3.12 (c). Fig. 3.12 (d) shows the

pattern after weaving all the strips.

In a similar manner, two sets of yarn

are woven to make a fabric. The yarns

are much thinner than our paper strips,

of course! Weaving of fabric is done on

looms (Fig. 3.13). The looms are either

hand operated or power operated.

Knitting

Have you noticed how sweaters are

knitted? In knitting, a single yarn is

used to make a piece of fabric (Fig. 3.14).

Have you ever pulled the yarn from a

torn pair of socks? What happens? A

single yarn gets pulled out continuously

as the fabric gets unravelled. Socks and

many other clothing items are made of

knitted fabrics. Knitting is done by

hand and also on machines.

Paheli wants to know if you have

seen any fabrics that are made

of the fibres on the outer covering

of coconut. What are these

fibres normally used for?

(b)

23FIBRE TO FABRIC

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

Weaving and knitting are used for

making different kinds of fabric.

These fabrics are used for a variety of

clothing items.

3.6 HISTORY OF CLOTHING MATERIAL

Have you ever wondered what materials

people used in ancient times for clothes?

It appears that in those times people

used the bark and big leaves of trees or

animal skins and furs to cover

themselves.

After people began to settle in

agricultural communities, they learnt to

weave twigs and grass into mats and

baskets. Vines, animal fleece or hair were

twisted together into long strands. These

were woven into fabrics. The early Indians

wore fabrics made out of cotton that grew

in the regions near the river Ganga. Flax

is also a plant that gives natural fibres.

In ancient Egypt, cotton as well as flax

were cultivated near the river Nile and

were used for making fabrics.

In those days, stitching was not

known. People simply draped the fabrics

around different parts of their body.

Many different ways of draping fabrics

were used. With the invention of the

sewing needle, people started stitching

fabrics to make clothes. Stitched clothes

have gone through many variations

since this invention. But, is it not

amazing that even today saree, dhoti,

lungi or turban is used as an un-stitched

piece of fabric?

Just as there is a large variety in the

food eaten all over our country, a large

variety exists also in fabrics and

clothing items.

nThere is a variety of clothing material or fabric, such as, cotton, silk,

wool and polyester.

Fabric

Cotton Rolls Fibre Yarn

Ginning Spinning

Knitting Weaving

loownottoC

cirbaF

erbiF

gnittinK

gninnipS

gnivaeW

nraY

24 SCIENCE

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

1. Classify the following fibres as natural or synthetic:

nylon, wool, cotton, silk, polyester, jute

2. State whether the following statements are true or false:

a) Yarn is made from fibres.

b) Spinning is a process of making fibres.

c) Jute is the outer covering of coconut.

d) The process of removing seed from cotton is called ginning.

e) Weaving of yarn makes a piece of fabric.

f) Silk fibre is obtained from the stem of a plant.

g) Polyester is a natural fibre.

3. Fill in the blanks:

a) Plant fibres are obtained from_________ and ________ .

b) Animals fibres are __________ and ___________ .

4. From which parts of the plant cotton and jute are obtained?

5. Name two items that are made from coconut fibre.

6. Explain the process of making yarn from fibre.

nFabrics are made from yarns, which in turn are made from fibres.

nFibres are either natural or synthetic. Cotton, wool, silk and jute are

some natural fibres, while nylon and polyester are some examples of

synthetic fibres.

nFibres like cotton and jute are obtained from plants.

nThe process of making yarn from fibres is called spinning.

nFabric from yarns is made by weaving and knitting.

SUGGESTED PROJECTS AND ACTIVITIES

1. Visit a nearby handloom or powerloom unit and observe the weaving or knitting

of fabric.

2. Find out if any crop is grown in your region for obtaining fibre. If yes, what is

it used for?

3. India has been a major producer of cotton and its fabric. India exports cotton

fabrics and items to many other countries. Find out, how it helps us?

25FIBRE TO FABRIC

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

Boojho knows that burning of

cotton yarn gives an odour similar

to burning paper. He is wondering

if he can assume that paper is also

made from plants.

4. Do you know that famous Sufi Saint and poet Kabir, was a weaver? Find out

about his life and teachings.

5. You can do an activity to identify the yarns of a fabric under the supervision

of your teacher or parents. Pull out six to eight yarns from the fabric. Hold one

end of the yarn with a tong and bring the other end over the flame of a candle.

Observe carefully. Do the yarns shrink away from the flame? Do the yarns

melt or burn? What type of odour is given off? Note down your observations.

If these are cotton yarns, they burn but do not shrink or melt. The burning

yarn gives an odour similar to burning paper. The silk yarn shrinks away

from the flame and burns but does not melt. It has the odour of charred meat.

The wool yarn also shrinks and burns but does not melt. It has a strong odour

of burning hair. The synthetic yarns shrink and burn. They also melt and

give out an odour similar to burning plastics.

26 SCIENCE

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

27FIBRE TO FABRIC

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

LOCAL TEXT

Fig. Devices for spinning (A) Spindle; (B) and (C) Charkha (Tareng)

(A) (B) (C)

LOCAL TEXT

FIBRE TO FABRIC 26

28 SCIENCE

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

27SORTING MATERIALS INTO GROUPS

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

Fig. 4.1 Objects around us

Sorting Materials into Groups

4.1 OBJECTS AROUND US

We have seen that our food and clothes

have so much variety in them. Not just

food and clothes, there is such a vast

variety of objects everywhere. We see

around us, a chair, a bullock cart, a

cycle, cooking utensils, books, clothes,

toys, water, stones and many other

objects. All these objects have different

shapes, colours and uses (Fig. 4.1).

Look around and identify objects

that are round in shape. Our list may

include a rubber ball, a football and a

glass marble. If we include objects that

are nearly round, our list could also

include objects like apples, oranges, and

an earthen pitcher (gharha). Suppose

we were looking for objects that are

edible. We might include all the items

that we have listed in Tables 1.1, 1.2

and 1.3 in Chapter 1. We might also

find that some of those round shaped

objects we just listed out, are also in

this group.

Let us say, we wish to make a group

of objects that are made of plastics.

Buckets, lunch boxes, toys, water

containers, pipes and many such

objects, may find a place in this group.

There are so many ways to group objects!

In the above examples we have grouped

objects on the basis of their shape or the

materials they are made from.

All objects around us are made of one

or more materials. These materials may

be glass, metal, plastics, wood, cotton,

paper, mud or soil. Can you think of

more examples of materials?

Activity 1

Let us collect as many objects as

possible, from around us. Each of us

could get some everyday objects from

home and we could also collect some

objects from the classroom or from

outside the school. What will we have

in our collection? Chalk, pencil,

notebook, rubber, duster, a hammer,

nail, soap, spoke of a wheel, bat,

28 SCIENCE

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

Boojho wants to know, whether

we found some materials that

were used for making more than

one type of an object.

matchbox, salt, potato. We can also list

objects that we can think of, but, cannot

bring to the classroom. For example,

wall, trees, doors, tractor, road.

Separate all objects from this

collection that are made from paper or

wood. This way we have divided all objects

into two groups. One group has the

objects that are made from paper or wood

while the other group has the objects

that are not made of these materials.

Similarly, we could separate the things

that are used for preparing food.

Let us be a little more systematic. List

all objects collected, in Table 4.1. Try to

identify the materials that each one is

made of. It would be fun to make this a

large table – collecting information

about as many objects as possible. It

may seem difficult to find out the

materials out of which some of these

objects are made. In such cases, discuss

with your friends, teacher and parents

to identify the materials.

Table 4.1 Objects and the materials

they are made of

Objects Materials they are

made of

Plate (thali)Steel, glass, plastics

(any other)

Pen Plastics, metal

Activity 2

Table 4.2 lists some common materials.

You can also add more materials in

Column 1 that are known to you. Now,

try and think of everyday objects you

know, that are made mainly of these

materials, and list them in Column 2.

Table 4.2 Different types of objects

that are made from the same

material

Material Objects made of

these materials

Wood Chair, table,

plough, bullock cart

and its wheels, ...

Paper Books, notebooks,

newspaper, toys,

calendars,...

Leather

Plastics

Cotton

What do we find from these tables?

First, we grouped objects in many

different ways. We then found that

objects around us are made of different

materials. At times, an object is made of

a single material. An object could also

be made of many materials. And then

again, one material could be used for

making many different objects. What

decides which material should be used

29SORTING MATERIALS INTO GROUPS

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

Fig. 4.2 Using a cloth tumbler

for making any given object? It seems

that we need to know more about

different materials.

4.2 PROPERTIES OF MATERIALS

Have you ever wondered why a tumbler

is not made with a piece of cloth? Recall

our experiments with pieces of cloth in

Chapter 3 and also keep in mind that

we generally use a tumbler to keep a

liquid. Therefore, would it not be silly,

if we were to make a tumbler out of cloth

(Fig 4.2)! What we need for a tumbler is

glass, plastics, metal or other such

material that will hold water. Similarly,

it would not be wise to use paper-like

materials for cooking vessels.

Appearance

Materials usually look different from

each other. Wood looks very different

from iron. Iron appears different from

copper or aluminium. At the same time,

there may be some similarities between

iron, copper and aluminium that are not

there in wood.

Activity 3

Collect small pieces of different materials –

paper, cardboard, wood, copper wire,

aluminium sheet, chalk. Do any of these

appear shiny? Separate the shiny

materials into a group.

Now, observe as the teacher cuts each

material into two pieces and look at the

freshly cut surface (Fig. 4.3). What do

you notice? Does the freshly cut surface

of some of these materials appear shiny?

Include these objects also in the group

of shiny materials.

Do you notice such a shine or lustre

in the other materials, cut them anyway

as you can? Repeat this in the class with

as many materials as possible and make

a list of those with and without lustre.

Instead of cutting, you can rub the

surface of material with sand paper to

see if it has lustre.

Fig. 4.3 Cutting pieces of materials to see if they

have lustre

We see then, that we choose a

material to make an object depending

on its properties, and the purpose for

which the object is to be used.

So, what are all the properties of

materials that would be important for

their usage? Some properties are

discussed here.

30 SCIENCE

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

Fig. 4.4 What disappears, what doesn’t?

Materials that have such lustre are

usually metals. Iron, copper, aluminium

and gold are examples of metals. Some

metals often lose their shine and

appear dull, because of the action of air

and moisture on them. We therefore,

notice the lustre, only on their freshly

cut surface. When you visit an

ironsmith or a workshop, look out for

freshly cut surfaces of metal rods to see

if they have lustre.

Hardness

When you press different materials with

your hands, some of them may be hard

to compress while others can be easily

compressed. Take a metal key and try

to scratch with it, the surface of a piece

of wood, aluminium, a piece of stone, a

nail, candle, chalk, any other material

or object. You can easily scratch some

materials, while some cannot be

scratched so easily. Materials which can

be compressed or scratched easily are

called soft while some other materials

which are difficult to compress are called

hard. For example, cotton or sponge is

soft while iron is hard.

In appearance, materials can have

different properties, like lustre,

hardness, be rough or smooth. Can you

think of other properties that describe

the appearance of a material?

Soluble or Insoluble?

Activity 4

Collect samples of some solid substances

such as sugar, salt, chalk powder, sand

and sawdust. Take five glasses or

beakers. Fill each one of them about two-

thirds with water. Add a small amount

(spoonful) of sugar to the first glass,

salt to the second and similarly, add

small amounts of the other substances

into the other glasses. Stir the contents

of each of them with a spoon. Wait for a

few minutes. Observe what happens to

the substances added to water (Fig. 4.4).

Note your observations as shown

in Table 4.3.

Table 4.3 Mixing different solid

materials in water

Substance Disappears in water/

does not disappear

Salt Disappears completely in

water

Sugar

Sand

Chalk

powder

Sawdust

You will notice that some substances

have completely disappeared or

dissolved in water. We say that these

substances are soluble in water. Other

substances do not mix with water and

do not disappear even after we stir for a

31SORTING MATERIALS INTO GROUPS

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

Fig. 4.5 (a) Some liquids mix well with

water while (b) some others do not

(a) (b)

Boojho suggests that we

also check if the liquids that we

used in Activity 5, mix well with

some liquid other than water.

Paheli is curious to know

whether gases also dissolve

in water.

long time. These substances are

insoluble in water.

Water plays an important role in the

functioning of our body because it can

dissolve a large number of substances.

Do liquids also dissolve in water?

Activity 5

Collect samples of vinegar, lemon juice,

mustard oil or coconut oil, kerosene or

any other liquid. Take a glass tumbler.

Fill it up to half with water. Add a few

spoonfuls of one liquid to this and stir

it well. Let it stand for five minutes.

Observe whether the liquid mixes with

water (Fig. 4.5). Repeat the same with

other liquids, as many different liquids

as are available to you. Write your

observations in Table 4.4.

Table 4.4 Solubility of some

common liquids in water

Liquid Mixes well/

Does not mix

Vinegar Mixes well

Lemon juice

Mustard oil

Coconut oil

Kerosene

Some gases are soluble in water

whereas others are not. Water, usually,

has small quantities of some gases

dissolved in it. For example, oxygen gas

dissolved in water is very important for

the survival of animals and plants that

live in water.

Objects may float or sink in

water

While doing Activity 4, you might have

noticed that the insoluble solids

separated out from water. You may have

also noticed this with some liquids in

Activity 5. Some of these materials that

did not mix with water, floated to the

surface of water. Others may have sunk

to the bottom of the tumbler, right? We

notice many examples of objects that

float in water or sink (Fig. 4.6). Dried

leaves fallen on the surface of a pond, a

stone that you throw into this pond, few

We notice that some liquids get

completely mixed with water. Some

others do not mix with water and form

a separate layer when kept aside for

some time.

32 SCIENCE

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

Figure 4.6 Some objects float in water while

others sink in it

drops of honey that you let fall into a

glass of water. What happens to all

of these?

Boojho would like you to give him

five examples each, of objects that float

and those that sink in water. What

about testing these same materials to

see if they float or sink in other liquids

like oil?

Transparency

You might have played the game of hide

and seek. Think of some places where

you would like to hide so that you are

not seen by others. Why did you choose

those places? Would you have tried to

hide behind a glass window? Obviously

not, as your friends can see through that

and spot you. Can you see through all

the materials? Those substances or

materials, through which things can be

seen, are called transparent (Fig. 4.7).

Glass, water, air and some plastics are

examples of transparent materials.

Shopkeepers usually prefer to keep

biscuits, sweets and other eatables in

transparent containers of glass or

plastic, so that buyers can easily see

these items (Fig. 4.8).

On the other hand, there are some

materials through which you are not

able to see. These materials are called

opaque. You cannot tell what is kept

in a closed wooden box, a cardboard

carton or a metal container. Wood,

cardboard and metals, are examples of

opaque materials.

Do we find that we can group all

materials and objects, without any

confusion, as either opaque or

transparent?

Activity 6

Take a sheet of paper and look through

it towards a lighted bulb. Make a note

of your observation. Now, put 2-3 drops

Fig. 4.8 Transparent bottles in a shop

Fig. 4.7 Looking through opaque, transparent or

translucent material

33SORTING MATERIALS INTO GROUPS

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

Hard

Insoluble

Lustre

Material

Metals

Opaque

Rough

Soluble

Translucent

Transparent

of some oil and spread it on the sheet of

paper. Look again towards the lighted

bulb through that portion of the paper

on which the oil has been spread. Do

you find that the bulb is more clearly

visible than before? But, can you see

clearly through the oiled paper? Is

everything on the other side of it visible?

Perhaps not. The materials through

which objects can be seen, but not

clearly, are known as translucent.

Remember the oily patch on paper when

we tested food items for presence of fats?

That was translucent too. Can you

think of some more examples of

translucent materials?

We can therefore group materials as

opaque, transparent and translucent.

Paheli suggests

covering the glass

of a torch with your

palm at a dark

place. Switch on

the torch and

observe the other

side of the palm.

She wants to know

whether palm of your hand is opaque,

transparent or translucent?

We learnt that materials differ in their

appearance and the way they mix in

water or other liquids. They may float

or sink in water or may be transparent,

opaque or translucent. Materials can be

grouped on the basis of similarities or

differences in their properties.

Why do we need to group materials?

In everyday life, we often group materials

for our convenience. At home, we

usually store things in such a manner

that similar objects are placed together.

Such an arrangement helps us to locate

them easily. Similarly, a grocer usually

keeps all type of biscuits at one corner

of his shop, all soaps at another while

grains and pulses are stored at some

other place.

There is another reason why we find

such grouping useful. Dividing

materials in groups makes it convenient

to study their properties and also

observe any patterns in these properties.

We will study more about this in

higher classes.

Fig. 4.9 Does torch

light pass through

your palm?

34 SCIENCE

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

nObjects around us are made up of a large variety of materials.

nA given material could be used to make a large number of objects. It is

also possible that an object could be made of a single material or of

many different types of materials.

nDifferent types of materials have different properties.

nSome materials are shiny in appearance while others are not. Some are

rough, some smooth. Similarly, some materials are hard, whereas some

others are soft.

nSome materials are soluble in water whereas some others are insoluble.

nSome materials such as glass, are transparent and some others such

as wood and metals are opaque. Some materials are translucent.

nMaterials are grouped together on the basis of similarities and differences

in their properties.

nThings are grouped together for convenience and to study their

properties.

1. Name five objects which can be made from wood.

2. Select those objects from the following which shine:

Glass bowl, plastic toy, steel spoon, cotton shirt

3. Match the objects given below with the materials from which they could be

made. Remember, an object could be made from more than one material and a

given material could be used for making many objects.

stcejbO slairetaM

kooB ssalG

relbmuT dooW

riahC repaP

yoT rehtaeL

seohS scitsalP

4. State whether the statements given below are True or False.

(i) Stone is transparent, while glass is opaque.

(ii) A notebook has lustre while eraser does not.

(iii) Chalk dissolves in water.

(iv) A piece of wood floats on water.

35SORTING MATERIALS INTO GROUPS

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

SUGGESTED ACTIVITY

1. You may have played a memory game with your friends. Several objects are

placed on a table, you are asked to observe them for a few minutes, go into

another room and write down the names of all objects that you can remember.

Play this game, with a difference! Ask all the participants in the game to

remember objects with some particular property while playing this memory

game — remember and write down the names of objects that were made of

wood or objects that are edible and so on. Have fun!

2. From a large collection of materials, make groups of objects having different

properties like transparency, solubility in water and other properties. In later

chapters you will also learn about properties of materials related to electricity

and magnetism. After making different groups from the collected materials,

try and find out if there are any patterns in these groups. For instance, do all

materials which have lustre conduct electricity?

(v) Sugar does not dissolve in water.

(vi) Oil mixes with water.

(vii) Sand settles down in water.

(viii) Vinegar dissolves in water.

5. Given below are the names of some objects and materials:

Water, basket ball, orange, sugar, globe, apple and earthen pitcher

Group them as:

(a) Round shaped and other shapes

(b) Eatables and non eatables

6.List all items known to you that float on water. Check and see if they will float on

an oil or kerosene.

7.Find the odd one out from the following:

a) Chair, Bed, Table, Baby, Cupboard

b) Rose, Jasmine, Boat, Marigold, Lotus

c) Aluminium, Iron, Copper, Silver, Sand

d) Sugar, Salt, Sand, Copper sulphate

36 SCIENCE

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

5Separation of Substances

Grain is separated from stalks, while

harvesting. Milk or curd is churned to

separate the butter (Fig. 5.2). As we

learned in Chapter 3, we gin cotton to

separate its seeds from the fibre.

Perhaps you might

have eaten salted

daliya or poha. If you

found that it had

chillies in it, you may

have carefully taken

them out before eating.

Suppose you are given a basket

containing mangoes and guavas and

asked to separate them. What would you

do? Pick out one kind and place them

in a separate container, right?

Seems easy, but what if the materials

we want to separate are much smaller

Fig. 5.1 Separating tea leaves with a strainer

Fig. 5.2 Butter is taken out by churning milk or

curd

But, why would we need to

separate substances like this

at all, is what Paheli wants

to know.

Activity 1

In Column 1 of Table 5.1, are given a

few processes of separation. The purpose

of separation and the way separated

components are used is mentioned in

Column 2 and 3 respectively. However,

the information given in Columns 2 and

3 is jumbled up. Can you match each

In our daily life, there are many

instances when we notice a substance

being separated from a mixture

of materials.

Tea leaves are separated from the

liquid with a strainer, while preparing

tea (Fig. 5.1).

than mango or guava? Imagine you are

given a glass of sand with salt mixed in

it. Impossible, even to think of

separating salt from this mixture by

picking out grains of sand by hand!

SEPARATION OF SUBSTANCES

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

process with its purpose and the way

separated components are used?

We see that, before we use a

substance, we need to separate harmful

or non-useful substances that may be

mixed with it. Sometimes, we separate

even useful components if we need to

use them separately.

The substances to be separated may

be particles of different sizes or

materials. These may be in any three

states of matter i.e., solid, liquid or gas.

So, how do we separate substances

mixed together if they have so many

different properties?

5.1 METHODS OF SEPARATION

We will discuss some simple methods of

separating substances that are mixed

together. You may come across some of

these methods being used in day to day

activities.

Handpicking

Activity 2

Bring a packet of food grain purchased

from a shop to the classroom. Now,

spread the grains on a sheet of paper.

Do you find only one kind of grain on

the sheet of paper? Are there pieces of

stone, husks, broken grain and particles

of any other grain in it? Now, remove

with your hand the pieces of stone,

husks and other grains from it.

This method of handpicking can

be used for separating slightly larger

sized impurities like the pieces of dirt,

stone, and husk from wheat, rice or

pulses (Fig. 5.3). The quantity of such

impurities is usually not very large.

In such situations, we find that

handpicking is a convenient method of

separating substances.

Table 5.1 Why do we separate substances?

Separation

process

Purpose for which we do

the separation

What do we do with the

separated components?

1) Separate

stones from rice

a) To separate two different,

but useful components.

i) We throw away the soild

component.

2) Churning milk

to obtain butter

b) To remove non-useful

components.

ii) We throw away the

impurities.

3) Separate tea

leaves

c) To remove impurities or

harmful components.

iii) We use both the

components.

Fig. 5.3 Handpicking stones from grain

Threshing

You must have seen bundles of wheat

or paddy stalks lying in fields after

38 SCIENCE

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

harvesting the crop. Stalks are dried in

the sun before the grain is separated

from them. Each stalk has many grain

seeds attached to it. Imagine the

number of grain seeds in hundreds of

bundles of stalk lying in the field! How

does the farmer separate grain seeds

from those bundles of stalks?

One may pluck mangoes or guavas

from the trees. But, grain seeds are

much smaller than mangoes or guavas.

So, plucking them from their stalks

would be impossible. How does one

separate grain seeds from their stalks?

The process that is used to separate

grain from stalks etc. is threshing. In

this process, the stalks are beaten to free

the grain seeds (Fig. 5.4). Sometimes,

this mixture on a plate or a newspaper.

Look at this mixture carefully. Can the

two different components be made out

easily? Are the sizes of particles of the

two components similar? Would it be

possible to separate the components by

handpicking?

Now, take your mixture to an open

ground and stand on a raised platform.

Put the mixture in a plate or sheet of

paper. Hold the plate or the sheet of

paper containing the mixture, at your

shoulder height. Tilt it slightly, so that

the mixture slides out slowly.

What happens? Do both the

components — sand and sawdust (or

powdered leaves) fall at the same place?

Is there a component that blows away?

Did the wind manage to separate the

two components?

This method of separating

components of a mixture is called

winnowing. Winnowing is used to

separate heavier and lighter components

of a mixture by wind or by blowing air.

Fig. 5.4 Threshing

threshing is done with the help of

bullocks. Machines are also used to

thresh large quantities of grain.

Winnowing

Activity 3

Make a mixture of dry sand with

sawdust or powdered dry leaves. Keep Fig. 5.5 Winnowing

soop

husk

grain

direction of the air

SEPARATION OF SUBSTANCES

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

This method is commonly used by

farmers to separate lighter husk particles

from heavier seeds of grain (Fig. 5.5).

The husk particles are carried away

by the wind. The seeds of grain get

separated and form a heap near the

platform for winnowing. The separated

husk is used for many purposes such

as fodder for cattles.

Sieving

Sometimes, we may wish to prepare a

dish with flour. We need to remove

impurities and bran that may be present

in it. What do we do? We use a sieve

and pour the flour into it (Fig. 5.6).

Sieving allows the fine flour particles

to pass through the holes of the sieve

while the bigger impurities remain on

the sieve.

In a flour mill, impurities like husk

and stones are removed from wheat

before grinding it. Usually, a bagful of

wheat is poured on a slanting sieve. The

sieving removes pieces of stones, stalk

and husk that may still remain with

wheat after threshing and winnowing.

to separate pebbles and stones from

sand (Fig. 5.7).

Activity 4

Bring a sieve and a small quantity of

flour from home, to the class. Sieve the

flour to separate any impurities in it.

Now, make a fine powder of chalk pieces

and mix it with the flour. Can we

separate the flour and the powdered

chalk by sieving?

Sieving is used when components of

a mixture have different sizes.

Sedimentation, Decantation

and Filtration

Sometimes, it may not be possible to

separate components of a mixture by

winnowing and handpicking. For

example, there may be lighter impurities

like dust or soil particles in rice or

pulses. How are such impurities

separated from rice or pulses before

cooking?

Rice or pulses are usually washed

before cooking. When you add water to

these, the impurities like dust particles

Fig. 5.6 Sieving

You may have also noticed similar

sieves being used at construction sites

Fig. 5.7 Pebbles and stones are removed from

sand by sieving

40 SCIENCE

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

get separated. These impurities go into

water. Now, what will sink to the bottom

of the vessel — rice or dust? Why? Have

you seen that the vessel is tilted to pour

out the dirty water?

When the heavier component in a

mixture settles after water is added to

it, the process is called sedimentation.

When the water (along with the dust) is

removed, the process is called

decantation (Fig. 5.8). Let us find a

few other mixtures that can be separated

through sedimentation and

decantation.

The same principle is used for

separating a mixture of two liquids that

do not mix with each other. For example,

oil and water from their mixture can be

separated by this process. If a mixture of

such liquids is allowed to stand for some

time, they form two separate layers. The

component that forms the top layer can

then be separated by decantation.

Let us again consider a mixure of a

solid and liquid. After preparing tea,

what do you do to remove the tea leaves?

Usually, we use stainer to remove tea

leaves. Try decantation. It helps a little.

But, do you still get a few leaves in your

tea? Now, pour the tea through a

strainer. Did all the tea leaves remain

in the strainer? This process is called

filtration (Fig. 5.1). Which method of

separating tea leaves from prepared tea

is better, decantation or filtration?

Let us now consider the example

of water that we use. Do all of us, at

all times, get safe water to drink?

Sometimes, water supplied through taps

may be muddy. The water collected from

ponds or rivers may also be muddy,

especially after rains. Let us see if we

can use some method of separation to

remove insoluble impurities like soil

from the water.

Activity 5

Collect some muddy water from a pond

or a river. If it is not available, mix some

soil to water in a glass. Let it stand for

half an hour. Observe the water

carefully and note your observations.

Does some soil settle at the bottom

of water? Why? What will you call this

process?

Now, slightly tilt the glass without

disturbing the water. Let the water from

the top flow into another glass (Fig. 5.8).

What will you call this process?

Is the water in the second glass still

muddy or brown in colour? Now filter

it. Did the tea strainer work? Let us try

filtering the water through a piece of

cloth. In a piece of cloth, small holes or

pores remain in between the woven

threads. These pores in a cloth can be

used as a filter.

If the water is still muddy, impurities

can be separated by a filter that has even

Fig. 5.8 Separating two components of a mixture

by sedimentation and decantation

undissolved

material

(soil)

mixture

(soil + water)

SEPARATION OF SUBSTANCES

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

Fruit and vegetable juices are usually

filtered before drinking to separate the

seeds and solid particles of pulp. The

method of filtration is also used in the

process of preparing cottage cheese

(paneer) in our homes. You might have

seen that for making paneer, a few drops

of lemon juice are added to milk as it

boils. This gives a mixture of particles

of solid paneer and a liquid. The paneer

is then separated by filtering the mixture

through a fine cloth or a strainer.

Evaporation

Activity 6

Add two spoons of salt to water in

another beaker and stir it well. Do you

smaller pores. A filter paper is one such

filter that has very fine pores in it.

Fig. 5.9 shows the steps involved in

using a filter paper. A filter paper folded

in the form of a cone is fixed onto a

funnel (Fig. 5.10). The mixture is then

poured on the filter paper. Solid

particles in the mixture do not pass

through it and remain on the filter.

Fig. 5.11 Heating a beaker containing salt water

see any change in the colour of water?

Can you see any salt in the beaker, after

stirring? Heat the beaker containing the

salt water (Fig. 5.11). Let the water boil

away. What is left in the beaker?

In this activity, we used the process

of evaporation, to separate a mixture of

water and salt.

The process of conversion of water

into its vapour is called evaporation.

The process of evaporation takes place

continuously wherever water is present.

Where do you think, salt comes

from? Sea water contains many salts

mixed in it. One of these salts is the

common salt. When sea water is allowed

to stand in shallow pits, water gets

heated by sunlight and slowly turns into

water vapour, through evaporation. In

a few days, the water evaporates

completely leaving behind the solid salts

(Fig. 5.12). Common salt is then

obtained from this mixture of salts by

further purification.

Fig. 5.9 Folding a filter

paper to make a cone

Fig. 5.10 Filtration

using a filter paper

42 SCIENCE

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

Use of more than one method

of separation

We have studied some methods for

separation of substances from their

mixtures. Often, one method is not

sufficient to separate the different

substances present in a mixture. In such

a situation, we need to use more than

one of these methods.

Activity 7

Take a mixture of sand and salt. How

will we separate these? We already saw

that handpicking would not be a

practical method for separating these.

Keep this mixture in a beaker and

add some water to it. Leave the beaker

aside for some time. Do you see the sand

settling down at the bottom? The sand

can be separated by decantation or

filtration. What does the decanted liquid

contain? Do you think this water

contains the salt which was there in the

mixture at the beginning?

Now, we need to separate salt and

water from the decanted liquid. Transfer

this liquid to a kettle and close its lid.

Heat the kettle for some time. Do you

notice steam coming out from the spout

of the kettle?

Take a metal plate with some ice on

it. Hold the plate just above the spout

of the kettle as shown in Fig. 5.13. What

do you observe? Let all the water in the

kettle boil off.

When the steam comes in contact

with the metal plate cooled with ice, it

condenses and forms liquid water. The

water drops that you observed falling

from the plate, were due to condensation

of steam. The process of conversion of

water vapour into its liquid form is

called condensation.

Did you ever see water drops

condensed under a plate that has been

used to cover a vessel containing milk

that has just been boiled?

After all the water has evaporated,

what is left behind in the kettle?

We have thus, separated salt, sand

and water using processes of

decantation, filtration, evaporation and

condensation.

Paheli faced a problem while

recovering salt mixed with sand. She

has mixed a packet of salt in a small

Fig. 5.12 Obtaining salt from sea water

Fig. 5.13 Evaporation and condensation

SEPARATION OF SUBSTANCES

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

amount of sand. She then tried the

method suggested in Activity 7, to

recover the salt. She found, however,

that she could recover only a small part

of the salt that she had taken. What

could have gone wrong?

Can water dissolve any

amount of a substance?

In chapter 4, we found that many

substances dissolve in water and form

a solution. We say that these substances

are soluble in water. What will happen

if we go on adding more and more of

these substances to a fixed quantity of

water?

Activity 8

You will need a beaker or a small pan, a

spoon, salt and water. Pour half a cup

of water in the beaker. Add one

teaspoonful of salt and stir it well, until

the salt dissolves completely (Fig 5.14).

Again add a teaspoonful of salt and stir

well. Go on adding salt, one teaspoonful

at a time, and stir.

After adding a few spoons of salt, do

you find that some salt remains

undissolved and settles at the bottom

of the beaker? If yes, this means that

no more salt can be dissolved in the

amount of water we have taken. The

solution is now said to be saturated.

Here is a hint as to what might have

gone wrong when Paheli tried to recover

large quantity of salt mixed with sand.

Perhaps the quantity of salt was much

more than that required to form a

saturated solution. The undissolved salt

would have remained mixed with the

sand and could not be recovered. She

could solve her problem by using a

larger quantity of water.

Suppose, she did not have sufficient

quantity of water to dissolve all the salt

in the mixture. Is there some way that

water could be made to dissolve more

salt before the solution gets saturated?

Let us try and help Paheli out.

Activity 9

Take some water in a beaker and mix

salt in it until it cannot dissolve any

more salt. This will give you a saturated

solution of salt in water.

Now, add a small quantity of salt to

this saturated solution and heat it. What

do you find? What happens to the

undissolved salt in the bottom of the

beaker? Does it dissolve, now? If yes,

can some more salt be dissolved in this

solution by heating it?

Let this hot solution cool. Does the

salt appear to settle at the bottom of the

beaker again?

The activity suggests that larger

quantity of salt can be dissolved in water

on heating.

Fig 5.14 Dissolving salt in water

44 SCIENCE

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

Does water dissolve equal amounts

of different soluble substances? Let us

find out.

Activity 10

Take two glasses and pour half a cup

of water in each of them. Add a teaspoon

of salt to one glass and stir till the salt

dissolves. Go on adding salt, one

teaspoon at a time, till the solution

saturates. Record the number of spoons

of salt that dissolved in the water, in

Table 5.2. Now, repeat the same

activity with sugar. Repeat this with

some other substances that are soluble

in water.

What do you notice from Table 5.2?

Do you find that water dissolves different

substances in different amounts?

Table 5.2

ecnatsbuS

fosnoopsforebmuN

tahtecnatsbus

retawnidevlossid

tlaS

raguS

We have discussed a few methods of

separating substances. Some of the

methods of separation presented in this

chapter are also used in a science

laboratory.

We also learnt that a solution is

prepared by dissolving a substance in a

liquid. A solution is said to be saturated

if it cannot dissolve more of the

substance in it.

gninruhC

noitasnednoC

noitatnaceD

noitaropavE

noitartliF

gnikcipdnaH

noitulosdetarutaS

noitatnemideS

gniveiS

noituloS

gnihserhT

gniwonniW

nHandpicking, winnowing, sieving, sedimentation, decantation and

filtration are some of the methods of separating substances from their

mixtures.

45SEPARATION OF SUBSTANCES

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

1. Why do we need to separate different components of a mixture? Give two

examples.

2. What is winnowing? Where is it used?

3. How will you separate husk or dirt particles from a given sample of pulses before

cooking.

4. What is sieving? Where is it used?

5. How will you separate sand and water from their mixture?

6. Is it possible to separate sugar mixed with wheat flour? If yes, how will you do it?

7. How would you obtain clear water from a sample of muddy water?

8. Fill up the blanks

(a) The method of separating seeds of paddy from its stalks is called ___________.

(b) When milk, cooled after boiling, is poured onto a piece of cloth the cream

(malai) is left behind on it. This process of separating cream from milk is an

example of ___________.

(d) Impurities settled at the bottom when muddy water was kept overnight in a

bucket. The clear water was then poured off from the top. The process of

separation used in this example is called ___________.

9. True or false?

(a) A mixture of milk and water can be separated by filtration.

(b) A mixture of powdered salt and sugar can be separated by the process of

winnowing.

nHusk and stones could be separated from grains by handpicking.

nHusk is separated from heavier seeds of grain by winnowing.

nDifference in the size of particles in a mixture is utilised to separate

them by the process of sieving and filtration.

nIn a mixture of sand and water, the heavier sand particles settle down

at the bottom and the water can be separated by decantation.

nFiltration can be used to separate components of a mixture of an insoluble

solid and a liquid.

nEvaporation is the process in which a liquid gets converted into its vapour.

Evaporation can be used to separate a solid dissolved in a liquid.

nA saturated solution is one in which no more of that substance can be

dissolved.

nMore of a substance can be dissolved in a solution by heating it.

nWater dissolves different amount of soluble substances in it.

46 SCIENCE

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

SUGGESTED PROJECTS AND ACTIVITIES

1. Visit a nearby dairy and report about the processes used to separate cream

from milk.

2. You have tried a number of methods to separate impurities like mud from

water. Sometimes, the water obtained after employing all these processes could

still be a little muddy. Let us see if we can remove even this impurity completely.

Take this filtered water in a glass. Tie a thread to a small piece of alum.

Suspend the piece of alum in the water and swirl. Did the water become clear?

What happened to the mud? This process is called loading. Talk to some elders

in your family to find out whether they have seen or used this process.

(d) Grain and husk can be separated with the process of decantation.

10. Lemonade is prepared by mixing lemon juice and sugar in water. You wish to

add ice to cool it. Should you add ice to the lemonade before or after dissolving

sugar? In which case would it be possible to dissolve more sugar?

THINGS TO SEE

“The winnowers”, painted by Gustav Courbet in 1853

Reproduced with permission from Museè de Beaus Arts, Nantes, France

SEPARATION OF SUBSTANCES

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”

LOCAL TEXT

Need for separating the components of a Mixture

We have learnt that we need to separate different components from a mixture to

select the useful components from the non-useful components. Threshing out the

paddy from the stalk during havesting is one such example. Each component of a

mixture possesses its own unique property which is not shared by any other

components in the mixture. Based on such unique property, components of a

mixture can be separated. You can observe many processes of separating the

components of mixture in your family or locality.

Winnowing

During harvesting, you may have observe winnowing

done by devices known as Phou-Indok in the field.

Yangkok Khappa is another example of winnowing

Hand Picking

A hand picking process called Phouman Khanba is

common in Manipur. It is performed by picking up

unwanted materials from the grains, paddy or pulses by

hand.

Exercise

True or False

(a) Rice and husk in the rice mills can be separated by

the wind produced by the electrice fan.

(b) Hand picking is a convenient method for removing

large number of stone from rice.

48 SCIENCE

SAMAGRA SHIKSHA MANIPUR “NOT FOR SALE”