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Textbook TeamAuthors

S.Shameem, Senior Lecturer, DIET, Triplicane, Chennai.R.Sivagama Sundari. DEEO, Chennai. V.Balamurugan. P.G.Teacher, Dr. Radhakrishnan Govt.(B), Hr. Sec. School, Tiruttani Thiruvallur District.H.Jayala Irince, P.G.Teacher, GHSS, Maduravoyal. Thiruvallur District.M.Shanthi, P.G.Teacher, Sri Vidhyalaya Mat.HSS, Gobichettipalayam, Erode District.M.Srivellingiri, H.M, P.U.M.School, Pongaliyur, K.M.Pattinam, Pollachi. Coimbatore District.N.Saravanan, B.T.Asst, Govt. High School, Kuppichipalayam, Erode District.S.Jayapriya, B.T.Asst,P.U.M.S, Kattumalayanur, Thiruvannamalai District. P.Devarajan, BRTE, Zone-2, Royapuram, Chennai. T.S.Sarasvathi, B.T.Asst, Govt. High School,Nattarasanpattu, Kanchipuram District.A.Julia Mary, BRTE, Villivakkam Block, Thiruvallur District.

IllustrationA.Kasiviswanathan, Art Master, Govt. Hr. Sec.School, Udayapatti, Salem District.M.Chinnasamy, Art Master, Govt. Hr. Sec.School, Kottur, Coimbatore District.

TranslatorsB.Ilangovan, Asst Hm, Karnataka Sanga Hr. Sec. School T.Nagar, Chennai.S.Thapasi, P.G.Asst, Wesley Hr. Sec. School, Chennai.R.Soundarapandiyan, P.G.Asst, Sir.M.Ct.M. Hr. Sec. School, Anna Nagar, Chennai.E.Sampath Kumar, B.T.Asst, Jg.V.V.Mat.Hr. Sec. School, Anna Nagar, Chennai.G.Angelin Ruby, T.G.T.Zion Mat Hr. Sec. School, Selaiyur,Tambaram, Kanchipuram District.Josephine Rosalind Eugene, B.T.Asst, St.Joseph A.I.Hr.Sec.School, Perambur, Chennai.P.Preetha, M.G.B.TAsst St.Joseph A.I. Hr. Sec.School.Perambur,Chennai.S.Usha, T. G .T. S.B.O.A Mat. Hr. Sec. School, Anna Nagar, Chennai.

ScienceStandard Six

Term IVolume 2

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Science is……

Why does the sun appear only in the day time? Why do the stars glow only at night? Why do plants grow towards the sunlight even when they are kept in a room?

The questions like What? Why? and How? can readily be given answers with the help of Science.

The things we use in our day to day life, for example, electrical equipments, various food items and sophisticated life style are gifts from the source of science.

Physics deals with our galaxy, earth and other planets, stars and their dynamic motions, light, sound and other related sources of science.

Chemistry deals with metals, non-metals, melting substances, odour and taste (salt or sweet) of materials used in our day to day life.

In the universe, the living organisms exist only in the earth. The study of herbs, shrubs, climbers, trees, domestic animals, wild animals, aquatic organisms, microbes and other life forms around us is called Biology.

The branch of science that deals with herbs, shrubs, climbers and trees is called Botany. The study of animals is known as Zoology.

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Our ancestors were nomads, hunting and wandering for food. Then, after several thousands of years, they learned to cultivate the food crops on their own.

Nowadays, many food crops like paddy, sugarcane, millet, coconut and vegetables are cultivated in villages for food.

What are the things we will buy if we visit a vegetable shop with our parents? Those will be a part of a plant, either a leaf or an unripe fruit.

coconut groove

Paddy fi eld

sugarcane fi eld

millet fi eld

1

vegetable farm

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Unit - 1

Mani visited his grandma’s house during holidays. There he bathed with his grandpa in the canal. He was affected with common cold the next day. He thought that his grandpa would take him to the doctor. Instead, his grandma gave him herbal medicine for three days and to his surprise, he was cured completely.

Now shall we list out the food items derived from the different parts Now shall we list out the food items derived from the different parts of the plant.

In addition to vegetables, cereals, pulses, fruits and oils, spices are also obtained from plants. Food plants are used for food. Food based industries depend on plants. Plants are useful to us in many ways. It is used in the preparation of food items such as chips, pickle, dhal powder, jam etc.

Medicinal plants:

Plants are used not only as food, but also as medicines to cure our diseases.Most of the medicines which we use in our daily life are produced from plant extracts.

50,000 to 75,000 tonnes mango pulp is been exported to foreign countries from Krishnagiri district of Tamilnadu every year .This yields good income for the farmers. It also increases the income of the nation.nation.

Plants that have medicinal properties are known as herbal plants.

Now a days, plant - based medicines are preferred by many people. World wide researches are

Food item Material required Plant part

SambarThoor dhal, Chilli, drumstick, Curry leaf, Turmeric powder

Seed unripe fruit, Leaf, Stem

Pepper rasam

Brinjal fry

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Uses of Herbal plants

Pea egg plant(Thuthuvalai) cures cold, cough

Neem(Vembhu)

destroys intestinalworms.

Carry me seed(Keezhanelli)

cures jaundice

Our ancestors said that if we consume plants having medicinal values, it will help us to be healthy and strong without diseases. So it was rightly said by our ancestors “Food is medicine”.

done to fi nd out the medicinal value of plants.

In our country, plants are being used from ancient days to cure several diseases.

The herbal plants grow naturally in forests, mountains and hills and some are found in the road sides.

Let us learn some of the medicinal values of herbal plants.

What herbal medicine would grandma have given to Mani? Find out from your grandma or elders at home and put it in writing.

Ask your elders and write down the simple medicinal practices done at home to cure stomachache, headache, and fever.

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Holy basil(Thulasi)

cures cold, cough,fever

Country borage

(Omavalli)

increases sweating,cures fever

cures mouth ulcer, regulates body

temperature

Turmeric(Manjal)

used as germicide and cosmetic

Veldt grape(Pirandai)

increases appetite,cures digestive

problem

Ginger(Inji)

Pepper(Milagu)

cures throat infection

Sweet fl ag(Vasambu)

cures abdominaldiseases

Gooseberry (Nelli)

cures digestive disorders

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We grow plants not only for food and medicine, but also for ornamentation, as construction materials and for other purposes.

Flowers and cosmeticsWe all love beautiful fl owers such

as rose, lily, jasmine, etc. Flowers play a key role in the preparation of cosmetics like bathing soap, talcum powder, deodorant and perfumes.

Discuss with your Parents or Discuss with your Parents or elders and fi ll up the following.

What are the ingredients needed to prepare dry ginger coffee?_____________________________Method of preparation__________________________________________________________Uses__________________________________________________________

SPICESMany a time while cooking we

can smell a pleasant smell. Have you ever wondered the reason for this smell? Spices which are added while cooking are the reason for this good smell.

Spices are got from many parts of plants. Spices give good smell and colour to food.

Spices increase the amount of food eaten and their digestion rate. Many parts of plants such as leaves,

stems and fl owers are used as spices.

Some spices are also used as medicines. Ginger, mint and sesame are used as medicines for common cold, fever and stomach ache.

Turmeric and clove are used as antibiotics and antiseptics.

Collect the herbs in and around in your area and organise a herbal exhibition in your class room. Discuss with your peer students about the name of the herbs, their medicinal value and part of the plants used as medicines.

Kerala is known as the Spice Garden of India

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Unit - 1

Parts of the plant used as spices

Fenugreek (Vendayam) Fennel (Sombu) Mustard (kadugu)

Underground stemGinger and turmeric are the stem of the plant found under the ground.

This does the function of food storage.

Cardamom (Elachi)

Unriped fruit Fruit Bark Leaves Flower bud

Dry ginger (Sukku) / Ginger Turmeric (Manjal) Dry ginger (Sukku) / Ginger Turmeric (Manjal)

Pepper (Milagu)

Cinnamon(Lavangam)

Mint(pudina)

Clove(Krambu)

Seed

Underground stem

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Leaf fi bresFibres are obtained from the

leaves of Aloevera and pineapple.

Jute

Aloe vera pineapple

Let us know:Now a days hemp is cultivated not only for jute, but also for some other pur-poses. It is used in the preparation of bio-plastics since it has 85% of cel-lulose. Bio-plastics are bio-degradable.

activity 3Write any ten

products made by using fi bres.

Long, thin, strong strand obtained from plants is known as fi bre.

Clothes, Jute and Gunny bags

The dress we wear, the jute and gunny bag we use are the products of plants.

Our cotton dress is the gift from cotton plants. Jute obtained from the plant Hemp is used to make gunny bags. Coir ropes are produced from the coconut fi bre. Fibres from the hemp plant are used to make gunny bags. Apart from this, fi bre plants are also used in making pillow, bed, mat and mattress.

There are many kinds of fi bres which are used to make cloth, net, and paper. Fibres are classifi ed on the source from which they are obtained.Stem fi bres

Plantain fi bre and jute are obtained from stem of their plants.

These are called as leaf fi bres.

External fi bresFibres obtained from the outer

region of the seed are known as external fi bres.eg. Cotton, Coconut, Silk cotton.Plants in construction

Parts of the plant used for building purposes are known as wood.

The dark inner region of the stem is called heartwood and the outer

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Teak: Construction material, furniture

Jack fruit Construction material,

Fruits

Eucalyptus tree Oil, paper

region is called as sapwood.

Sapwood helps to conduct water. heartwood gives strength and rigidity to the plant. It is stronger than sapwood. Mostly Heartwood is not infected by fungus, termite, borers. It is hard and resistant to fungus due to the presence of gum, latex, resin and oil. It is more lustrous and is used for building purposes. Sapwood is infected by fungus and termites.

Many trees grow in and around our place. Knowing about their uses, will be more useful for our life.

GIFT OF NATURE - PLANTSHerbs, shrubs and trees are

inevitable for our life. Plants provide us the basic needs such as food, clothing and shelter. Forests are necessary for getting rainfall. Trees purify the air. So, we understand that it is harmful if we destroy trees!

Let us not stop with just learning about it, but get involved in constructive activities like

creating gardens in the backyard and

planting trees in the school campus.

Activity 4

List the furniture in your house and fi nd out from your elders from which tree these are made.S.No. Name of the item Name of the tree

1.

2.

3.

4.

5.

Mango treeconstruction

materials, fruits

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Silk cotton tree Match stick,match box,

toys, bed, pillow

Coconut tree Thatching

construction, tender coconut, coconut

Pine treeRailway sleepers,

ship building

Mulberry treeTennis racket and

Hockey stick

Willow tree: Sports materials, Cricket bat

Babul bark tree (Karuvelam tree) Parts

of bullock cart

Sandal tree :Sandal, craft, furniture

1. Do you know that a small garden can be created near the window of your kitchen? Fill the bucket with soil and sow seeds of medicinal plants, greens, coriander and tomato. Water them regularly. Thus, a small garden can be created in your house. Now share your experience in the class room.

2. In countries like Japan, Russia and Cuba, vegetables are cultivated on the open terrace. Like this, you can also get benefi tted by forming garden on the open terrace of your school or house and cultivate pumpkin, snake gourd, tomato and bitter gourd.

Extended activities

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Unit - 1Discuss in groups and collect information about herbs,

shrubs, and trees found in your surroundings.

Plants Name Uses

Facts fi le

1. Thickest African tree found in Zimbabwe is Boabab tree.2. Orange trees yield fruits for about 400 years.3. Raffl esia produces the largest fl owers. The diameter of the fl ower is one

metre.4. Red wood tree doesn't easily catch fi re5. From a watermelan, 6,00,000 watermelon plants can be produced and

from them watermelon weighing 180 tonne can be obtained.

Raffl esia Redwood tree Boabob tree

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Stem

Seed

Fruit Leaf

Root

Flower

Vegetable

FoodProducts

I.Fill in :Evaluation

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2. Rearrange the letters and fi nd out the name of the plant. (Eg: Ricturme-Turmeric)1. fi nlagerdy’s - ____________________ 2. reeogosbry - ____________________3. mutayhcrsnhem - ____________________4. irragonefut - ____________________5. werfl ouns - ____________________

3. Names of some useful plants are hidden in the following checker. Find out atleast ten and write their uses in one or two words.

4. Some places are very popular for their products, like Tanjore for Paddy, Madurai for Jasmine, and Kumbakonam for Betel leaves.Refer the library and write such famous places known for their products.

P E P P E R 0 S E P C A C T U S

T Q M U L B E R R Y R T H V G U

S N A K E G 0 U R D L 0 I F S T

K 0 N I 0 N W Z N 0 K M P I N E

E U C A L Y P T U S J A E I W B

N A J C D G A R L I C T G U V M

E X 0 K E B F H C A L 0 D T Q L

E N P B R I N J A L P M A N G 0

M B K L M N 0 B A N A N A Q R W

R Z M A Z C 0 C 0 N U T S X Y R

Evaluation

5. Choose the correct answer

1. Plants with medicinal value are called

a) pulses b) scented plants

c) medicinal plants d) barks

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2. Of the following, which is the seed part of the plant?

a) thoor dhal b) veldt grape

c) banana d) turmeric

3. Select the food-related industry from the following

a) coir making b) gardening

c) cotton cultivation d) pickle-making

4. Name the unripe fruit that we have to consume for blood purifi cation.

a) gooseberry b) neem

c) bottle gourd d) keezhanelli

5. Name the tree used in paper industry.

a) Teak b) Eucalyptus

c) Coconut tree d) Sandal wood tree

6. Match the following:

Trees Uses

Eucalyptus Parts of bullock cart

Silk cotton Railway sleepers

Coconut Tennis racket and Hockey stick

Mulberry Thatching, construction

Pine Match box

Babul bark tree Oil, papers

7. State whether the following sentences are true or false. Correct the statement.

1. Purple fruited pea egg plant is used as medicine for jaundice.

2. Ginger is the root of the plant.

3. Veldt grape is a medicinal plant.

4. Cloveis the Seed of the plant.

5. Silk cotton tree is used to make match box.

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Unit - 18. Answer the following:

1. Where do the scent / odour in bathing soap and perfume come from?2. Write about the plants and parts of the plant from which coir ropes, and

gunny bags are made.3. Where do medicinal plants grow?4. Name the plants that yield cooking oil.5. Write down the benefi ts of adding spices in food.

6. Differentiate between heartwood and sapwood.

9. Think and answer.

1. How will you explain to a foreign tourist about any fi ve medicinal plants of our country?

2. We cut and use the trees, but at the same time it is instructed "Trees should not be cut off". How to fi nd solution to this contradiction?

3. Only heartwood is used to make furniture. Is it correct? Give reason?

FURTHER REFERENCEWebsites:

http://en.wikipedia.org/wiki/foodhttp://www.moomilk.com/tour.htm

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2We know about the cartoon hero

Popeye. Don't we? In this story, Popeye, the sailor is thin and weak. But his opponent is obese and strong. His name is Brutus. Popeye is often beaten by him.

Immediately, Popeye consumes spinach. It gives him immense strength and that's all, his opponent Brutus is defeated.

appear stronger. But, it is not really healthy so.

It is not advisable to eat noodles. Noodles we eat are different from the noodles eaten by Chinese. They consume home-made noodles.

But we consume industry-made artifi cially fl avoured noodles.

Food items like bubble gum, roadside food contaminated with housefl y, factory made chemicals added, tinned or fast food are harmful to our health. It is good to avoid these food items. Why? Then what kind of food should we consume?

What are healthy food items? What are the unhealthy food items?

I'm Popeye; you can watch me

on Television cartoons, Video games, Advertisements

and Films.

Substances that provide nutrients

for the body are called food.

This cartoon story illustrates the importance of greens like spinach. It is true, that the food we consume must be nutritious. Obese person may

Food Habits

List out the food items that you consume in the following space provided.

Morning _______________________________________________

Afternoon________________________________________________

Night _________________________________________________

Activity 1

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What are the various sources of food?

Food items obtained from plants and animals:

The root, stem, leaf, fl ower, vegetable, fruit and seed of the plants are used as food for us. Different food items like milk, egg and meat are obtained from animals.

List out the food items obtained from plants and animals in the following table

Food items obtained from plants Food items obtained fromanimals

______________________

______________________

______________________

______________________

______________________

______________________

______________________

______________________

______________________

______________________

Nutrients

The constituents of the food which are essential for the body are called nutrients. Does a food contain more than one nutrient? Do you know any food without nutrients? Why do we need nutrients?

Types of Nutrient

• Carbohydrates - Provide energy

• Proteins - Help in growth

• Fats - Provide energy

• Vitamins - Help in physiological activities

• Minerals - Act as regulators in physiological activities

• Water - Transports food, regulates body temperature.

Activity 2

Take a cucumber. Cut it into small slices. Water oozes out while cutting! Why?

Activity 3

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Let us know

Vitamins will be lost when vegetables and fruits are washed after cutting.

Adequate amount of vitamins and minerals are present in the peels of fruits and vegetables.

We lose vitamins and minerals in cereals and

pulses by washing it several

times.Defi ciency Diseases:Diseases caused due to the defi ciency of nutrients in food that we eat are Diseases caused due to the defi ciency of nutrients in food that we eat are called defi ciency diseases.called defi ciency diseases.

Water content in vegetables, fruits and food items:Name of the food Water content

Cucumber 95%

Potato 75%

Mushroom 92%

A bread slice 25%

Egg 73%

Milk 87%

Water melon 99%

Defi ciency diseases and their symptoms

Nutrient : Protein

Food source: Fish, meat, egg(albumin), milk, peas, cereals

Defi ciency disease :Kwashiorkar (children from 1-5 age)

Symptoms:retarded growth, pot belly, swollen limbs.

Nutrient : Protein

Food source: Fish, meat, egg(albumin), milk, peas, cereals

Defi ciency disease : Marasmus

Symptoms:Thin limbs, weak appearance, enlarged head, loss of weight, retarded physical and mental growth.

Kwashiorkar

Marasmus

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Vitamin A

Fish liver oil, egg, milk, ghee, butter, carrot, corn, yellow fruits, greens.

Night blindness Defective vision, blindness in dim light

Vitamin B

Whole grains, pulses, unpolished rice, milk, fi sh, meat, peas, gram, raw vegetables

Beri-beri Unhealthy nerve, muscle fatigue

Nutrient Food source: Defi ciencydisease Symptoms

Vitamins

Vitamin C

Orange, lemon, gooseberry, green chilies, tomato.

Scurvy Bleeding gums

Vitamin D

Fish liver oil, milk, egg. It is also produced in the skin with the help of sunlight.

Rickets Weak and bow bones

Vitamin E

Vegetable oils, green vegetables, whole wheat, Mango, Apple, Greens

Infertility Sterility and reduction of immunity

Vitamin KGreen vegetables, Tomato, Cabbage, Egg, Milk and milk products.

Haemorrahage (blood does not clot)

Loss of excessive blood even for a small hurt

Minerals

Calcium Milk, Fish, Wheat, Green Gram

Disintegration of bones and teeth Weak bones and teeth.

Iron Meat, Apple, Greens, Dates Anaemia Body fatigue. Giddiness.

Iodine Milk, Iodized Salt, Prawn, Crab Goitre Infl ammation in neck

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We can avoid diseases caused by defi ciency by consuming nutritious food

Scurvy Goitre

Balanced dietA food that contains all the nutrients in the right proportion is a balanced

diet. Go through the following table.

1.Cereals:Rice, Wheat, Ragi (Finger millet) Bajra (Pearl millet), Sorghum, Corn Barley, Rye

Carbohydrate, protein, a small amount of lipid, vitamin B,folic acid, iron, fi bre.

2.Pulses:Red gram, Black gram,Green gram, Horse gram,Bengal gram, Chick pea,Pea, Soya beans, Country beans etc.,

More proteins, a small amount of lipid, vitamin B, folic acid, iron, fi bre

3.

Milk and meat products:Milk, Ghee, Curd, Yogurt, Skimmed milk,

Protein, lipid, vitamin B, cal-cium

Chicken, Liver, Fish, Egg, Mutton. Protein, lipid, vitamin B

4.Fruits and Vegetables:Mango, Guava, TomatoPapaya, Orange, Water melon, Sweet lime, Grapes

Carotenoid, vitamin A,vitamin C, Iron, calcium

Gooseberry, Greens, Drumstick leaves, Coriander, Lettuce, Spring onion.

A small amount of lipid, carotenoid, vitamin B2, folic acid, calcium, iron, fi bre

Carrot, Brinjal, Lady’s fi nger, Capsicum, Country bean, Onion, Drum-stick, Caulifl ower.

Carotenoid, folic acid, calcium, Iron fi bre.

5.Ghee, Oils: Butter, Ghee, Vanaspathi, Cooking oils like Groundnut oil, Coconut oil, Gingely oil.

Lipid, Essential fatty acids

6. Sugar, Jaggery Carbohydrate, iron.

S.No Food category Nutrients present

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Nutrition:

How do living organisms get energy from these food substances? Ingestion, digestion, absorption and assimilation are the various stages of nutrition. Organisms consume both solid and liquid food substances by various methods.

Types of nutrition

1. Autotrophic nutrition

Mode of nutrition in which an organism prepares its own food is called autotrophic nutrition. E.g.: Green plants, Euglena. They prepare their own food by photosynthesis.

2. Heterotrophic nutrition

The mode of nutrition in which an organism depends on other organisms for food as they cannot prepare their own food is called heterotrophic nutrition.

Jaggery provides more benefi ts to the body than sugar

Nutrition is the mode of intake of food.

Name of any one of the grains, pulses, fruits, vegetables, tubers and dry seeds should be written by the students. Then they must discuss and know the nutritional value of these food substances. Then they must be divided into small groups. Each group must fi nd whether the food substances written by them make up a balanced diet

Activity 4

Let us know

Will it be enough for all the age group to have same quantity and same type of food?

Is it possible to get balanced diet for less price?

Preparation of starch (sugar) by the plants with the help of sunlight, CO2 water and chlorophyll is photosynthesis.

Carbon-di-oxide

Oxygen

Sun light

Water

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Animals based on nutrition:Animals which feed only on plants are called herbivores e.g. goat, cattle. Animals which feed only on plants are called herbivores e.g. goat, cattle. Animals which feed on other animals are called carnivores e.g. tiger. Animals Animals which feed on other animals are called carnivores e.g. tiger. Animals which feed on both plants and animals are called omnivores e.g. crow.which feed on both plants and animals are called omnivores e.g. crow.

Drosera

Types of Heterotrophic nutritionParasitic nutrition:

The mode of nutrition in which an organism depends on another organism food its food and survival is called parasitic nutrition.The plant cuscuta depends of other plants for food. It is an example for parasitic nutrition.

Types of parasites:

Ectoparasites

Organisms like head loves, leech, etc. are found attached to leech, etc. are found attached to the outer surface of the body and the outer surface of the body and get nourishment from the host. get nourishment from the host. So, these are called as Ectoparasites.So, these are called as Ectoparasites.

Endoparasites

Round worm lives inside the body (gut) and derives food from the intestine. So it is an endoparasite.

Saprophytes

In saprophytic nutrition, the organism decomposes the dead plant and animal substances and converts them into simple molecules and absorbs them through their body wall.E.g. Mushroom.

Discuss with your teacher how does the non green plants and animals prepare their own food?

3. Special type of nutritionPlants like Nepenthes, Drosera,

and Utricularia are green in colour and Utricularia are green in colour and are autotrophic.

Since they are found in nitrogen defi cient soil, they trap insects and kill them to get nitrogen from them. So they are called insectivorous plants.

CuscutaScientifi c Name :Cuscuta refl exia

Local Name:

Ammaiyaar koonthal/Sadathaari/Thanga kodi(m«ikah® Tªjš/rljhç/ j§f¡bfho)

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Name of the animal Herbivorous Carnivorous Omnivorous

CockroachCockroach

DeerDeer

LionLion

________________________

________________________

________________________

Can you write the names of animals that you know and mention their mode of nutrition?

Activity 5

1. Be happy

2. Maintain weight according to height

3. Do regular exercise and involve ingames

4.Avoid fried food items

5. Do not smoke

What are the ways to preventheart disease?

Which is a good food?We have to maintain our organs

in a good condition to lead a healthy life for a long time. It is based on the choice of food we consume.

It is necessary to take care of organs like heart, kidney and lungs. Good exercises and games are required. Junk foods and fried items should be avoided. Instead, food items containing protein and fi bre like

Extended activity

1. On a particular day, the students can list out the various food items they consumed along with the nutrients. By forming small groups, students have to discuss whether the food they consumed is a balanced diet? This will be benefi cial to all the students.

2. List out the food items that you like and dislike in the diet that you take everyday.

peas, cabbage and greens can be added in daily diet.

Steamed fi sh items and brinjal rich in ascorbic acid, prevent heart diseases.

We have to add vegetables equally with our food containing starch like rice, wheat, bajra, maize and ragi.

Doctors also say that some kind of fruit should be taken along with the diet.

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Think for a few secondsForm small groups and discuss the follwing content

You might have observed variety of food items are served in marriage halls and parties. Are they consuming all the food items or wasting it?

Is wasting food correct ?

What is the reason for wasting food ?

What are the remedial measures you would suggest to avoid wastage of food ?

My favourite food

Name of the food Nutrients Use

The food I dislike Name of the food Nutrients Effect

“Health is wealth”

EvaluationFill in the blanks:1. Disease caused due to proteins defi ciency is____________

(Marasmus/Night blindness)2. Defi ciency of Vitamin C causes________________ (Scurvy/Rickets)3. _________is an omnivore.(Crow/goat)4. Milk is rich in_________(calcium/Iron)5. _________regulate the physiological activities.(Protein/Minerals).6. ____________is used to strengthen the bone.(Calcium/Iron)7. ____________is saprophytic in nutrition.(Euglena/Mushroom).8. Anaemia is caused due to defi ciency of_________(Iron/Protein).9. ________is synthesized in skin with the help of sunlight. (Vitamin B / Vitamin D).10. Rickets is a___________defi ciency disease.( Vitamin A / Vitamin D).

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Mahesh! You become so fat like a blotted balloon because you drink

softdrinks while watching TV.Come… let us eat this mango and play.

No…no….. I am not coming Suresh; I don’t like to play.I will get

fever if I play.

II) Fill in:

Types of nutrition

Heterotrophic nutrition

Parasitic nutrition

Endoparasite

a) Among the two, whose attitude is correct? Why?b) From the following activities which will lead us to have healthy and a long

life. include more vegetables and fruits in diet. wake up early in the morning. watching T.V till late night. eating more fast food. participating in playing games like cricket , swimming and chess.

III. Think and answer:

1. Observe the following picture.

__________________

____________________

__________________ __________________

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2. Mala’s gum became infl ammated and started bleeding .Mala’s mother was frightened and took her to the doctor. What would the doctor have said as a reason for this disease? What kind of food doctor would have prescribed to Mala?

3. Should we wash the fruits and vegetables before or after cutting?Give reasons for your answer.

4. Few food items are placed on the table. Arthy wanted to select and eat the food which is rich in nutrients and healthy. You too can help her.

Milk

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Answer the following question:1. What is nutrient?2. Mention the different kinds of nutrients and its functions.3. Why does few plants feed on insects?4. What kind of food should be taken to prevent night blindness?5. What is Balanced diet?

FURTHER REFERENCEWebsites:

http://en.wikipedia.org/wiki/Defi ciency_diseases

http://www.diethealthclub.com

Let us know

We should avoid intake of artifi cially coloured foods like kesari and cotton candy. The chemicals added in it are harmful to us.

When you eat food chew and taste the food. Avoid eating food while watching TV or talking as you may eat more. This leads to obesity and causes many other diseases.

Vegetables, greens should be taken in raw or half-boiled. By doing this we can avoid loss of nutrients

Eating leftover food kept in the refrigerator, the next day leads to health disorder.

Consuming bottled drinks, packed chips, oil fried food items which are sold in shops is harmful to our health.

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Changes Around Us

Kalpana Chawla

3Kalpana Chawla was the fi rst Indian wom-

an who travelled to the space. This is an ex-cerpt from the interview given by her in the year 1997 when she returned from space .

Interviewer: How did you feel when you fl ew in the space? What were the changes you felt?

Kalpana Chawla :- In the beginning, all parts of the body seemed to lose weight.I was not able to feel any of my body parts, as our body loses weight in space. I was crossing India with excitement as the space shuttle was whirling with high speed. The Gangetic plains looked like a thin line, Africa looked like a desert and the river Nile was like a thin streak. I went round the whole world within one and a half hour. I observed with wonder, the changes of day and night within short span of time. The tremendous changes in the different phases of moon from New moon to Full moon within a short duration created thrill and amazement. Everything took place very fast.

How do you feel when you read her statements? Is it not wonderful? The slow and natural changes that take place on earth seemed to take place at a faster rate while we travel in the space.

What are the changes we come across, when we return from our vacation?

We notice :

■ the dried up canals■ the newly laid road■ the rusted bicycle.

During the space travel kalpana chawla observed many changes like day and night which is due to rotation of the Earth. Shall we also observe the and night which is due to rotation of the Earth. Shall we also observe the changes around us starting from the seasonal changes like rainy to winter, changes around us starting from the seasonal changes like rainy to winter, winter to summwinter to summer?.

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Fill in the blanks with the given hints.1.The_______and _______of the child has increased.

2.The_______changes during day and night

3.The _______and the_______change during ripening of a mango,

(Hints: temprature, weight, taste, height, colour)

Hence changes in colour, temperature, place, shape, and size of the substances are considered as changes.Slow and Fast Changes

My Inference: All changes take place in ________________________ (the same/different) time duration.

Activity 1Discuss in small groups about the time duration for the

changes to take place.

ChangesDuration (few hours/ days/

weeks/months/ years)Growth of a child

Rusting of iron

Germination of a seed

The cooking of food

Curdling of milk

Changes that take place in a few hours, days months or years are called slow changes.

Look at the pictures given below and discuss in groups about the changes Look at the pictures given below and discuss in groups about the changes taking place.

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Trees which are buried under the earth nearly 34 crore years ago had undergone

many changes and turned into coal.

Take a cup of Petrol and a cup of Water and place them in Sunlight. Observe the changes and identify the slow and fast change.

1. Evaporation of water is_______________2. Evaporation of Petrol is ______________

Activity 2

Reversible and Irreversible Changes

Take a piece of paper and make a model of rocket as shown in the picture. Shall we unfold it after playing? Can you get back the same piece of paper? What do you infer?____________________________

Activity 3

Burning of a paper, bursting of crackers, glowing of an electric bulb take place in a few seconds or minutes. Isn’t it?place in a few seconds or minutes. Isn’t it?

The changes that take place in a short duration of time are called fast changes.

Fast changes

Slow Change

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Take a balloon and infl ate it by blowing air .After sometime release the air from it. Does the balloon get back its original shape?

What do you infer? _______________________________

Infl ate the same balloon and tie it using a thread. Pierce it with a bell pin. Can you infl ate the balloon again?

What do you infer? ______________________

_______________________________________

Activity 4

In some changes, the substance can be brought back to its original In some changes, the substance can be brought back to its original state. Such changes are called reversible changes.

The change in which the substance cannot be converted back into its The change in which the substance cannot be converted back into its original form is called Irreversible change.

I have seen workers laying road using black substance (Tar). Is melting of tar a reversible

change? or irreversible change?

Let us know?You would have seen some hard metals like gold, silver, You would have seen some hard metals like gold, silver,

and Iron being used to make ornaments and instruments. and Iron being used to make ornaments and instruments. In this process, metals are heated, melted and cast into In this process, metals are heated, melted and cast into desired shapes. On cooling they become hard. This is also desired shapes. On cooling they become hard. This is also a reversible change.a reversible change.

Can we get back the green vegetables from cooked ones? The batter from Idly or dosa? Raw rice from cooked rice?

Is it possible to get back the original substances in the above changes ? ________________________.(yes/No)

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Desirable and Undesirable Changes:

Are all changes that take place around us useful? Look at the pictures and Are all changes that take place around us useful? Look at the pictures and write whether the changes are useful to us or not.write whether the changes are useful to us or not.

Shall we classify the following changesReversible Irreversible

Reversible change 1. Curdling of milk 1. Curdling of milk 1. Curdling of milk 1. Curdling of milk 1. Curdling of milk 1. Curdling of milk Irreversible changeMelting of ice 2. Melting of ice _______________Melting of ice 2. Melting of ice _______________Melting of ice 2. Melting of ice _________________________________ 3. Burning of wood _________________________________ 3. Burning of wood _________________________________ 3. Burning of wood _________________________________ 4. Batter into Idly _________________________________ 4. Batter into Idly _________________________________ 4. Batter into Idly _________________________________ 5. Evaporation of water _________________________________ 5. Evaporation of water _________________________________ 5. Evaporation of water _________________________________ 6. Greying of hair _________________________________ 6. Greying of hair _________________________________ 6. Greying of hair _______________

Changes like raining, ripening of fruits are useful to us. Such useful changes are called are called desirable changes.

Changes like spoiling of food, eruption of volcano are not liked by us, as they are harmful and not useful to us. Changes which are not useful to us as they are harmful and not useful to us. Changes which are not useful to us are called are called undesirable changes.

Spoiling of food Blooming of bud into fl ower

Rusting of iron Ripening of fruit Breaking of Glass

Irreversible

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Periodic and Non-Periodic ChangesLook at the calendar and complete the tabular Column;

Month New Moon (Date /Day)

Full Moon(Date /Day)

Pendulum clock

Day and Night

Phases of Moon

More examples for Periodic Changes

How many days are there between a new moon day and a full Moon day?Do the new Moon and full Moon occur at regular time interval?We understand that the new Moon and full Moon occur at regular time in-

terval. Hence the changes that occur at regular time interval are called Peri-odic changes.

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1. Take a small amount of detergent powder in your palm and add water? How do you feel?

2. Take a small amount of quick lime in a beaker and add water to it. Touch the beaker. How do you feel?

S.No. Periodic changes Non-periodic changes.

1. Occur at regular time interval. Do not occur at regular time interval

2.Can be predicted e.g. weather.

Cannot be predicted e.g. earth quake.

Look at the pictures given below.Can you predict when will these changes happen?Will they take place at regular time interval?

We cannot predict how and when above given changes will occur. So, the changes that do not occur at regular time interval are called non-periodic the changes that do not occur at regular time interval are called non-periodic changes.changes.

Let us learn the differences between the periodic and non-periodic changes.

Exothermic and Endothermic ChangesDo the following activities and record your inference in the table.

Acti vity 5

Eruption of volcano Earth quake

Land slide Accident

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3. Take a small amount of glucose in a beaker and add water to it. Now touch the beaker. How do you feel?

4. Take a small amount of water in a beaker. Add Ammonium chloride salt and stir it. Touch the beaker. How do you feel?

Experiment No. My inference

1.

2.

3.

4.

Changes in which heat is liberated are called exothermic changes. Ex . : burning of match stick, dissolution of detergent or washing soda in water.

Changes in which heat is absorbed are called endothermic changes.Ex. : Dissolution of glucose or ammonium chloride in water.

An invention from Nature.

Let us know.

We can create new things by closely observing the Nature .

Invention of Velcro by George Mestral in the year 1948. is a right example for this.

George Mestral used to go for a walk with his pet dog daily. One day he found that some seeds were hooked on his clothes and on the fur of his dog. He observed these seeds under a microscope and found some hook like structures on them. Based on this he tried to create a new thing.

This led him to the invention of Velcro. It has tiny hooks which can attach to the objects. Today velcro is widely used in bags, footwear and clothes.

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Using a thermometer measure the temperature of your class room from morning to evening and record in the tabular column. Know the changes in temperature.

DayTemperature

Morning Noon EveningMonday

Tuesday

Wednesday

Thursday

Friday

Acti vity 6

1.Mention the months during which we have summer season in our state._________________________________________2.During which months do we have winter season?_________________________________________3.During which months do we have rainy season?_________________________________________4.Do we get the above seasons during the same months every year?_________________________________________5.Under what type of change do you classify these seasonal changes?_________________________________________

Select two students from each class of your school and record their age,height, and weight. See the changes in their height, weight with the increase in their age.

Acti vity 7

Have you seen pot making? The potter is making the pot by heating wet clay. When can you get back the wet clay from the pot? (before heating /after heating) Discuss in small groups and fi nd the changes that take place in this process.

Acti vity 8

Acti vity 5

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Evaluation

I. Fill in the blanks and question marks:

Changes

Based onspeed

Based on time interval

Based on use

On the basisof reversibility

Based on heat

Desirable change

Reversible Change

e.g._______

e.g._______

e.g.e.g._______

e.g._______

e.g._______e.g._______

e.g._____________________

e.g._____________________

e.g.______________

e.g._______

?

?

?

?

?

?

??

II.Choose the correct answer1.Release of the compressed spring is _______

a)irreversible change b)reversible change

c)non-periodic change d)undesirable change

2. Spoilage of food is_________

a)reversible change b)fast change

c)undesirable change d)periodic change.

3. Dissolution of washing soda in water is___________

a)exothermic change b)irreversible change

c)undesirable change d)slow change.

4.Which of the following changes is non-periodic?

a)heart beat b)earth quake

c) occurrence of day and night d)oscillation of pendulum.

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III. Identify the changes in the following..a)Tsunami b)Swingingc)Occurrence of New Moon and Full Moon d)Melting of wax

IV. Answer the following.1. Give fi ve examples for desirable and undesirable changes.2. What type of change is an earthquake? Why?3. What is meant by slow change?4. What is an irreversible change? Give example.

V. Reason out the following questions

1. You have broken your favourite toy. Can you mend it ? What type of change does this belong to?

2. Meena and Nisha were about to have their lunch in their school. Nisha was not able to eat her lunch as her food was stale and spoiled. So Meena shared her food with Nisha . In the above situation,

a)What kind of change is spoilage of food?

b)What are the possible reasons for the spoiling of food ?

c)What are the evil effects of consuming of spoilt food?

d)Mention some of the methods adopted at your home to preserve food from spoilage.

3. Mention any fi ve changes that take place in your kitchen. Identify the kind of changes each belong to.

e.g.Preparation of chapathi - Slow change, desirable change, irreversible change.

Websites:

Further reference

www.simplescience.nethttp://www.bbc.co.uk/school/scienceclips/ages/10-11/rev-irrev-changes.htmhttp://www.learnnext.com/class6/science/changes-around-us.htm

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4Measurement

On a holiday Ezhil went to market with his father. First they went to a grocer’s shop. Ezhil’s father asked for the following.

Rice - 10 kg

Bengal gram - 500 gm

Groundnut oil - 2 litre

Ghee - 200 millilitre

The shopkeeper used a balance for measuring rice and bengal gram. He measured oil and ghee with a measuring jar.

They went to a fl ower shop and bought 5 cubit garland. Then they went to a textile showroom and selected a shirt material and asked 2 metre. The shopkeeper measured 2 metre of the cloth with a metre scale and gave them.

They went to a vegetable shop and asked for the following vegetables.

Lady’s fi nger-1kg

Green chillies-100gm

Onions-2kg

The shopkeeper weighed the vegetables with the help

of a balance. On their way, they went to a fruit stall and asked for a dozen bananas.

The shopkeeper counted and gave 12 bananas. After buying fruits they returned home. Ezhil had a doubt and asked his father, “Why do we need to order different items in different terms?”

In order to clear his doubt, his father asked him to prepare a list of the items purchased, their quantities and the instruments used for measuring them. Ezhil started preparing the list. Shall we help Ezhil?

Electronic balance

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From the above activity we have learnt that metre scale, balance , clock, measuring jar, etc. are measuring instruments.

What is measurement?Now, shall we measure the length

of our class room cupboard using a metre scale? Have you measured the length? If it is 2 metre then 2 is the magnitude and metre is the unit of length. Metre is a fi xed quantity but the quantity 2 is to be determined.Here the length of the cupboard is two times length of 1 metre.

Can we measure the mass of your school bag using a balance? If it is 3

kilogram, here 3 is to be determined. Kilogram is the unit of mass. That is, the mass of the bag is 3 times the mass of 1 kilogram.

Similarly, if it takes 20 minute to reach your school from home, then 20 is to be determined and minute is the unit of time.

Measurement is a process of comparison of an unknown quantity with a standard quantity of the same kind. Here metre, kilogram and minute are units. We have learnt that many physical quantities have both magnitude and unit.

Activity 1

Item Quantity Measuring Instrument

What are the instruments used to measure the following? Discuss in small groups and write them down.

1. Shirt material: __________________________2. Sugar: __________________________3. Cooking oil: __________________________4. Tomatoes: __________________________5. Length of your science text book: __________________________6. Time taken to reach school: __________________________7. Kerosene: __________________________8. Duration of tamil period: __________________________

Activity 2

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In the above activity even though length of the same table is measured, each one gets a different value. It is because the length of hand span differs from person to person. That is why measurement of length of garland in cubit by you and shopkeeper differs. Now can you measure the length of the same table by metre scale. Did all of you get the same value? what do we infer from this?

Hence cubit, hand span are not standard units. Metre, kilogram and second are the standard units Measurement of a quantity by different people should give the same value. This is called standard measurement. The units which are used for standard measurement are called standard units. Now shall we learn about fundamental quantities?

Fundamental quantitiesLength, Mass and Time are called

as fundamental quantities, because they are not to be expressed in terms

of other physical quantities

The units which are used to measure the fundamental quantities are called fundamental units.

SI system(System International Units)

In early days people in different parts of the world used different system of units for measuring length, mass and time. A few systems of units are,

1.FPS system

(Foot, Pound, Second)

2.CGS system

(Centimetre, Gram, Second)

3.M KS system

(Metre, Kilogram, Second) In order to overcome the diffi culties of using different systems of units, an International system was adopted in 1960. This was accepted by scientists all over the world.

Each of you, measure the length of the table in your classroom in terms of hand span. Fill up the following table.

Name of the Student Length of the table in hand span

1. ___________________ ___________________

2. ___________________ ___________________

3. ___________________ ___________________

4. ___________________ ___________________

Activity 3

The need for Standard Unit


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This system is called SI System. Shall we know the SI units of length, mass and time?

Physical quantity SI Unit Symbol

Length Metre mMass Kilogram kgTime Second s

Measurement of length

Draw a straight line in your note book. Plot two points A and Bon the line.

Measure the distance between the two points using a scale. What you have measured now is length. The distance between two points is called length. The SI unit of length is metre.

To measure length we use measuring tape, metre scale etc.

Know yourself• Length of cloth required for stitching your shirt• Distance of your home from school• Distance of your neighbouring town from home.• Distance of the state capital from your place.

• Shall we write down the different units of length used in the above activities?

A B

Shall we measure the length of the following and write them inproper units?Length of your pencil _________________Length of your thumb _________________Length of your eraser _________________Length of a leaf _________________Length of your pen nib _________________

Length of the nail of your little fi nger _________________

Activity 4

Multiples and submultiples of length

In the above activity, larger distances such as the distance between two places are expressed in

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Metre

Foot

KilometreHand Span

kilometre. This is called multiple of length. We express smaller lengths such as length of a pencil, pen nib etc. in centimetre and millimetre. These are called sub multiples.

Units of length

Physical quantity

SI unit Multiples Sub multiples

Length Metre Kilometre Millimetre,Centimetre

1 metre = 1000 millimetre

1 metre = 100 centimetre

1 kilometre = 1000 metre

Have you ever gone to a market? How do they measure rice, pulses, vegetables etc.? What instrument do they use to measure? Why do they not use the units millimetre and centi-metre in measuring rice, pulses, vegetables etc.? In what units do they measure? Discuss with your friends and fi nd out the answer.

Measurement of mass

Activity 5


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Physical balance

Among the three, a handful of rice, a handful of sand and handful of cotton, which one is heavier?

Carefully observe the wrapper of the following items and write down masses mentioned on it.

Mass of toilet soap ________________

Mass of washing soap ________________

Mass of a biscuit packet ________________

Activity 6

Activity 7

Sand is heavier because the amount of matter contained in sand is more than the amount of matter contained in rice and cotton.

Know yourself

The quantity of rice purchased per month at home.The quantity of vegetables used at home per day.

The mass of a body is the amount of matter contained in it. The SI unit of mass is kilogram. We use beam balance, physical balance and electronic bal-ance for measuring mass.

Physical quantity SI unit Multiples Sub multiples

Mass Kilogram quintal, metric tonne gram, milligram

From the above activity we have learnt that all the quantities are not mea-sured in the same unit. Different units are used for different quantities.

Multiples and sub multiples of mass

The mass of sugarcane, cotton etc. larger than 1 kilogram are measured in quintal and metric tonne. These are called multiples of mass. Similarly, the mass less than 1 kilogram is measured in gram and the mass less than 1 gram is measured in milligram. These are called sub multiples of mass.

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1 gram = 1000 milligram

1 kilogram = 1000 gram

1quintal = 100kilogram1 metric tonne = 1000 kilogram

Measurement of time

We perform many activities in our day-to-day life. Many events take place, but duration of each event differs.

Look at the following activities. Discuss in small groups and tabulate the events/activities according to their duration.

1. Time taken for bathing2. Duration of sleep3. Working hours of your school4. Time taken to blink your eyes5. Time taken for ripening of fruits6. Time taken for a plant to grow into a tree7. Time taken for curdling of milk8. Time taken to weave a saree9. Time interval between a new moon and full moon10. Duration of child to become a grandfather/grandmother11. Time taken for a paddy to grow 12. Duration between quarterly and half-yearly examination 13. Time of fall of a coconut from a coconut tree

Duration of child to become a grandfather/grandmother

Activity 8

Events/activities

occurring in second

Events/activities occurring in minute

Events/ activities

occurring in hours

Events/ activities

occurring in days / months

Events/ activities

occurring in years


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From the above events / activities, we have learnt that we use different units for measuring time.

Time is defi ned as the interval between two events. The SI unit of time is second.

For measuring time we use pendulum clock, wrist watch, wall clock, stop clock etc. In olden days people used sundial, sand clock, water clock etc. For measuring

time accurately nowadays we use electronic clock and atomic clock.

Multiples and sub multiples of time

Time interval larger than 1 second is expressed in minute, hour, day, week, month, year etc. These are called multiples of time. Any time interval less than 1 second is expressed in millisecond, microsecond etc. These are called sub multiples of time.

Physical quantity SI unit multiples sub multiples

Time second minute, hour, day, week, month, year

millisecond, microsecond

1 minute= 60 second

1 hour= 60 minute

1 day= 24 hour

1 year= 365 1/4 days

1 second= 1000 millisecond

1 second= 1000000 microsecond

Unit - 4

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I. Choose the correct answer.

1. SI unit of length is

a) Centimetre b) millimetre c) metre d)kilometre

2. SI unit of mass is

a) gram b) kilogram c) milligram d) centigram

3. 1 metric tonne is equal to

a) 1000 kilogram b) 100 kilogram c) 1 kilogram d) 10 kilogram

4. SI unit of time is

a) second b) minute c) week d) day

5.1 hour = ____________ seconds.

a) 60 b) 3600 c) 24 d) 1000

II.Fill in the blanks.

1. One metre = _________ centimetre

2. One kilometre = _________ metre

3. One quintal = _________ kilogram

4. One minute = _________ second

III. Match the following with the correct units

1. Thickness of a fi ve rupee coin - kilometre

2. Breadth of a classroom - centimetre

3. Distance between two places - millimetre

4. Height of your friend - metre

IV. Fill in the blanks with the correct answer.

1. The mass of gold is measured in the units ____________(gram/metre)

2. Rice, sugar etc are measured in the units ____________(milligram/kilogram)

3. Generally sugarcane is weighed in the units____________(tonne/gram)

4. The mass of the chemicals present in a tablet are expressed in the units____________ (milligram/kilogram)

V. Arrange the following units in ascending order.

Year, second, month, micro seconds, hour, minute, week, millisecond.


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VI.Find the answer

1) Ravi took 90 minutes to draw a picture. Kumar took 1 hour to draw the same picture. Who took more time to draw? How much more time did he take ?

2) Thread and metre scale are provided to you, using that try to measure the length of the given curved line AB.

VII.Answer the following questions

1. Defi ne measurement and unit.

2. What is the signifi cance of standard units?

3. What are fundamental quantities? Why are they called so?

4. What are the SI units of length, mass, and time? Mention their symbols.

5. Expand the following

(i) FPS (ii) CGS (iii) MKS (iv) SI

the length of the given curved line AB.

AB

Project

1. Measure the length and breadth of your class room and write them in foot, hand span, centimetre and metre.

2. Make a model of a sand clock. a) Using the model of a sand clock you have made, fi nd the time taken for the sand to completely come down from the upper part to the lower part.b) Find your heart beat and pulse rate for the same time taken for the sand to completely come down from the upper part to the lower part.

Let us know The length of the largest sea animal, blue whale measures 30metres

approximately. Mass of the sun = 1.99 x 1030 kilogram Mass of the earth = 5.98 x 1024 kilogram

(mass of the sun is 3,20,000 times heavier than the earth)

Unit - 4

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Motion

We look at different objects in our daily life .Of them, many move from one place to another place. Some of them remain stationary. With our experience, shall we do the following activity?

On your way to school, observe your surroundings and classify the objects under moving and stationary objects

Objects in motion Objects at rest _____________ _____________

_____________ _____________

From the above activity we have learnt that some objects move and some remain stationary.

Can we fi nd out whether an object is at rest or in motion only by observing them directly?

From the above discussion, we see that some objects change their position with time. Even though in some cases. We do not see the objects changing their position directly we come to know their motion from other effects.

If an object does not change its position with respect to time, it is said to be stationary.

If the object changes its position with respect to time then it is said to be in motion.

Have you travelled in a bus? When

Acti vity 1

Do the earth, air etc. move ? If they move, how do we know? We may get more information through a small group discussion

Acti vity 2


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you look out from a moving bus, do the trees, houses, lamp post appear to be stationary or in motion? Share your experience in small groups.

Akilan had two friends, Mugilan and Selvam. Akilan invited his friends to his town for a circus show. The three friends went to the circus and enjoyed the funny dance of the clown. Akilan returned home and his friends reached the bus terminus and got into a bus. The bus passed by Akilan’s house. As Akilan was in the sit-out, he waved hands to his friends.

Next day when Akilan met his friends in school, he shared his experience with his friends. Akilan said, “When I was in the sit-out, I saw you in the moving bus and I waved hands”.

Mukilan and Selvam said, “When you waved your hands we were in the moving bus. You and your house appeared to move backwards”.

What do we learn from this?

An object may appear to be stationary for one observer and appear to be moving for another. An object is at rest in relation to a certain set of objects and moving in relation to another set of objects. This implies that rest and motion are relative terms.

Motion is defi ned as the change of position of an object with respect to time.

Are the following motions same or different type? Discuss in small groups and classify.

How do we differentiate rest and motion?

Unit - 4

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1. Motion of a sprinter running a 100 m race2. Motion of a coconut falling from a tree3. Marching of soldiers4. Motion of the tip of hands of clock5. Movement of your hand when you write on a notebook6. Motion of the moon around the earth7. Motion of a ball in a foot ball match8. Motion of the earth revolving around the sun9. Motion of children playing on a sliding board10. Motion of the wagging tail of a dog11. Motion of children playing in a playground12. Motion of fl ies and mosquitoes13. Motion of children playing in a swing14. Motion of fl apping of elephant’s ears15. Motion of people in a bazaar16. Motion of people on a carnival day17. Motion of a spinning top18. Motion of opening and closing of a draw

Activity 3

Motion

Moving in a straight line

From the above activity, we have come to know that there are different types of motion.

Moving in a circle

Moving in a random manner

Moving back and forth/ left and right

Types of motion.Linear motion

Did you observe the vehicle moving along a straight road and a coconut

falling from a tree? What type of path did they take during their motion. Like wise, When an object moves along a straight line, it is said to be in linear


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motion. Motion of a body dropped from the top of a building and motion of a lift are examples for linear motion.

Circular motion

Take a stone, tie a thread to it and whirl it with your hand and observe the motion of the stone. Is the stone moving along a circular path? In this motion we can see, in any point in the circular path the distance of the stone from the centre of the circle (hand) remains the same.

Similarly we can see the motion of the child in the merry go round. Here also the distance between the child and the centre of the merry go round remains same in each and every point of the circular path.

From this, it is clear that if an object moves along a circular path,it is said to be in circular motion. Motion of the tip of hands of a clock and a point marked on the blade of the fan are some more examples for circular motion.

Rotational Motion

If a body revolves about an axis, it is said to be in rotational motion.

Eg. Spinning topMotion of a fan Motion of a merry go round

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Periodic motion

If an object repeats same type of motion at regular intervals of time it is said to be in periodic motion.

Rotational m

otion

Linear motion

Eg : Motion of a child in a swing Motion of pendulum in a wall clock

Motion of the string of veena while plucking

Motion of the moon revolving around the earth

Motion of the earth revolving around the sun

Random Motion When an object moves at

different speeds and in different

Can you think of any other object performing more than one type of motion simultaneously? Explain.

direction, it is said to be in random motion.

Eg. A fi sh swimming in a tank The movement of a foot ball

during a gameMultiple Motion

Can a body perform more than one type of motion at a time? We ride a bicycle. What type of motion does the wheel perform? What type of motion does the cycle perform?

The motion of the wheels of a bicycle is rotational, whereas the motion of the bicycle is linear. The wheels of a bicycle perform rotational as well as linear motion simultaneously. Similarly, a rolling ball and a drilling machine perform more than one type of motion simultaneously.of motion simultaneously.


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Science Today

Robot

Issac Asimov is called as the Father of Robot. It is he who named the machine as Robot (derived from Philippines language). Robot is a human machine. We programme the machine (Robot) to do the work we want it to do.

The machinery parts of Robot follow and implement the commands already programmed. Robots are run by heavy batteries. Robot’s brain is nothing but an electronic chip. The movements of Robot are controlled by electronic chip or computer. Nowadays well designed Robots are used for complicated and minute clinical surgeries. Very soon we may have Robots in our homes to do house hold work.

Evaluation

I. Choose the correct answer.

1.Movement of a branch of a tree in an is an example fora) Linear Motion b) Circular Motionc) Periodic Motion d) Rotational Motion

2.The motion of a rolling ball is _________________ motiona) Circular b) Linearc) Rotational d) Multiple

3. Who is the father of Robot?a) Sir Issac Newton b) Galileoc) Issac Asimov d) Thomas Alva Edison

How nice would it be to have a Robot to do our home work?

Imagine and draw the various activities, a Robot can do in your school.

Robot

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1. From the given picture, identify objects which are,In Motion

1.______________ 2.______________ 3.______________ At Rest

1.______________ 2.______________ 3.______________

2. Classify the following pictures based on the kind of motion. Among them identify the pictures which work on more than one kind of motion.

III. Fill in the blanks .

1. The movement of the needle in a sewing machine is _____________(linear motion, random motion)

2. The rotation of an object about an axis is _____________(linear, rotational motion)

3. Motion is defi ned as the change of _____________ of an object with respect to time. (position, mass)

IV. Give reasons for the following. 1. Name the organ in your body which works in periodic motion.

II. Look at the picture and answer the following .

After 5 seconds


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2. Is there any difference between a child who plays on a merry-go-round and a child who takes part in a 50m race?

3. Name the types of motion possessed by children playing in a playground. Give reasons.

4. What is the name of the instrument in the given picture ? Specify its uses. What type of motion does it perform while in operation?

V. Answer the following.1. When do you say that an object is in motion?2. Distinguish between linear motion and circular motion.3. What is rotational motion? Give example.4. What is periodic motion? Give example.

Do it yourselfSpread a large sheet of white paper on the

ground and keep a little sugar on it. Ants are likely to be attracted to the sugar and you will fi nd many ants crawling on the sheet of paper soon. For any one ant, try and make a small mark with a pencil near its position when it has just crawled on to the sheet of paper. Keep marking its position often a few seconds as it moves along on the sheet of paper. After some time, shake the paper free of the sugar and the ants, and connect the different points you have marked with arrows to show the direction in which the ant was moving. Each point you have marked shows where the ant moved to, in intervals of a few seconds.

Motion seems to be some kind of a change in the position of an object with time, isn't it?

FURTHER REFERENCE

Websites:

http://www.tutorvista.com/content/science/science-i/motion/types- motion.phphttp://en.wikipedia.org/wiki/measurement

www.arvindguptatoys.com

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Magnetism 5You might have seen magnets.

Have you ever enjoyed playing with them?

Why does the door of a refrigerator close by itself after opening?

Because the magnets are attached to the pin-holder and the refrigerator.

Already we know that magnet attracts pins, iron pieces and iron particles in sand. Cranes are used to lift heavy iron loads. Powerful magnets

Why do the pins stick to the pin holder placed on headmaster's / headmistress's table?

Powerful electromagnets are used to operate electromagnetic trains, lifts and escalators.

Discovery of magnets

How magnets were discovered? It is an interesting story.

It is said that, there was a shepherd named Magnes, who lived in Magnesia in Asia minor.

He used to take his herd of sheep and goats to the nearby mountains for grazing. He would take a stick with

are used in cranes.

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People have discovered that certain rocks have the property of attracting pieces of iron.

In early days Chinese navigators used magnets to fi nd the direction.

The magnetites are the natural magnets. They are called as magnetic stones.

Natural magnets do not have defi nite shape.

When a magnet is freely suspended, it always comes to rest in north- south direction. That is why they are called as leading stones or load stones.

him to control his herd. The stick had him to control his herd. The stick had a small piece of iron attached to one a small piece of iron attached to one end.end.

One day he was surprised to fi nd that he had to pull hard to free his stick that he had to pull hard to free his stick from a rock on the mountain side. from a rock on the mountain side.

It seemed as though the stick was being attracted by the rock. being attracted by the rock.

He thought that the rock was God. The rock was a natural magnet and it The rock was a natural magnet and it attracted the iron tip of the shepherd's attracted the iron tip of the shepherd's stick. stick.

It is said that this is how natural magnets were discovered.magnets were discovered.

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Substances attracted by magnets

Substances not attracted by magnets

Ring magnetBar magnet Horse shoe magnet

Let us know? Magnets attract not only articles made up of Iron but it also attracts Nickel and Cobalt.

After the method of magnetization of iron plate came into practice, we start-ed making different types of magnets and using them.

Such man made magnets are called Artifi cial magnets. Here some of the shapes of artifi cial magnets used in our day –today- life are listed below.

What type of Substances are attracted by magnets?Shall we fi nd out whether pen cap, plain pins, pencil, blade, nail, chalk

piece, iron ball, plastic scale, wooden scale and coin are attracted by magnet or not? Shall we discuss in small groups and list them?

We understand that, magnet attracts certain substances whereas some other substances do not get attracted.

The substances that are attracted by a magnet are called magnetic substances.

The substances that do not get attracted by a magnet are called non-magnetic substances.Does magnet have poles?

Is it not an interesting question? It is better to fi nd out by ourselves.

To perform a simple experiment, it is suffi cient to have iron fi lings and a magnet. Spread some iron fi lings on a sheet of paper. Now place a bar a sheet of paper. Now place a bar magnet on the iron fi lings. What do you observe? The iron fi lings stick all over the magnet, but more iron fi lings stick to the ends. Even in a horseshoe magnet more iron fi lings stick to the two ends.

The ends of a magnet has the strongest magnetic force. So most

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There are several methods of There are several methods of making artifi cial magnets.Let us learn the simplest one.

Take a nail /a piece of Iron. place it on a table.

Now take a bar magnet and place one of its poles near one edge of the a nail/a piece of Iron and rub from one end to another end without changing the direction of the pole of the magnet.

Repeat the process for 30 to 40 times.

Bring a pin or some iron fi llings

Magnetic compassMagnetic compass is a circular disc

on which a small needle is pivoted at its centre. This needle can rotate freely and always points in the north-south direction.

Different directions ( North, South, East, and west) are marked on the compass. The magnetic needle always rests in north-south direction. By using this magnetic compass we can fi nd out different directions

of the iron fi llings cling near both the ends of the magnet. They are called poles of the magnet.

Which is north pole? Which is south pole?

The poles of a magnet are easily found by freely suspending the found by freely suspending the magnet as shown in the diagram. magnet as shown in the diagram.

A freely suspended magnet always comes to rest in north-south direction comes to rest in north-south direction after being disturbed. after being disturbed.

North seeking pole is called north pole. South seeking pole is called pole. South seeking pole is called south pole.south pole.

This property of a magnet to fi nd out directions is used in a magnetic out directions is used in a magnetic compass. compass.

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Shall we fi nd out what happens when two bar magnets are brought closer?

Attraction? or repulsion?

When we bring two north poles of two bar magnets closer as shown in the fi gure they move away from each other. Similarly when two south poles of two bar magnets are brought closer they too move away from each other.

Like poles repel each other.

Unlike poles attract each other.

Do the magnets lose thier properties ? When?

Magnets lose their properties if they are,

heated

dropped from a height

hit with hammer

When a north pole and a south pole are brought closer, they pull towards each other.

When heated

When dropped

near a nail /a piece of Iron to check whether it has become a magnet.If not, continue the process for some more time.

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Storage of magnets

Improper storage can also cause magnets to lose their properties. To magnets to lose their properties. To keep them safe, bar magnets should keep them safe, bar magnets should be kept in pairs with their unlike poles be kept in pairs with their unlike poles on the same side. they must be on the same side. they must be separated by a piece of wood while separated by a piece of wood while two pieces of soft iron should be two pieces of soft iron should be placed across their ends. placed across their ends.

For horse-shoe magnet oneshould keep a piece of iron across the should keep a piece of iron across the poles.poles.

Let us knowMagnets lose their properties if we keep it near the cassettes, mobiles,

televisions, compact disks and the computer.

Some facts . . .

1.Electromagnets are used in giant wheels.

2.In 1600, English scientist William Gilbert proposed that earth behaves like a giant magnet.

Bar magnet

Horse shoe magnet

Soft iron

Bar magnetBar magnet

Soft iron

Wooden piece

Horse shoe magnet

When hammered

Soft iron

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Science today

Shall we learn about electromagnetic train?

Electromagnetic train is also called as suspension train. In France it is called as fl ying train. It does not require diesel, petrol or any other fuel.

The technology in which the property of magnetic attraction and repulsion used gave birth to super fast electromagnetic trains.

How does the electro magnetic train work?

Electromagnetic trains do not have wheels.Powerful electromagnets are attached to the bottom of the train as well as on the track. The north pole of the electromagnet on the track faces upwards and the north pole of the electromagnet on the train, faces downwards. The north pole in the track repels the north pole on the train and levitates the train. The electric current that changes constantly allows a change in polarity of electromagnets. This change in polarity pushes and pulls the train.

Electromagnetic train runs faster than ordinary train. Another signifi cance of electromagnetic train is that it does not make noise. We can see electromagnetic train in Japan, China, France, Germany and America.

Electromagnetic train

Write any 5 differences between a train and an electromagnetic train. (First difference is given)1. Electro magnetic trains do not have

wheels whereas ordinary trains have.

2. ___________________________

3. ___________________________

4. ___________________________

5. ___________________________

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EvaluationI. Choose the correct answer

1. It is a natural magneta) Bar magnet b) Magnetitec) Ring magnet d) Horse-shoe magnet

2. An object that is attracted by magnet.a) wooden piece b) plain pins c) eraser d) a piece of cloth

3. Mariner’s compass was fi rst used bya) Indian b) Europeanc) Chinese d) Egyptian

4. A freely suspended magnet always comes to rest approximately in the _____________ directiona) North - east b) South - westc) East - west d) North - south

5. Magnets lose their properties when it is a) used b)stored c) hit with hammer d)cleaned6. Mariner’s compass is used to fi nd the

a) speed b) displacement c) direction d)motion

II. Circle the odd ones and give reasons .

1. Bar magnet, magnetite, ring magnet , horseshoe magnet2. Iron nail, pins, rubber tube , needle

3. Lift, escalator, electro magnetic train, electric bulb

4. Attraction, repulsion, pointing direction, illumination

III. Think and answer

1. You are provided with a bar magnet without labelling the poles of the magnet and iron fi llings. Using this.

a) How will you identify the poles of the magnet?b) Which point of the bar magnet attracts more iron fi llings? Why?

2. You are provided with an iron needle. How will you magnetize it ?

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A B

Plain pins

Substances attracted by

magnets

Chalk piece

Substances not attracted by not attracted by not attracted by

magnets

Let us muse upon

With the help of your teacher fi nd the direction in which the fl ag pole, Principal's room, laboratory and play ground are located in your school.

FURTHER REFERENCE

Websites:http://www.school-for-champions.com/science/magnetism.htm

http://en.wikipedia.org/wiki/magnetite

3. Two bar magnets are given in the fi gure A and B. By the property of attraction, 3. Two bar magnets are given in the fi gure A and B. By the property of attraction, identify the North pole and the South pole in the bar magnet (B)

4. Take a glass of water with a few paper clips inside. How will you take out the paper clips without putting your hands.

IV. Answer the following

1. What are artifi cial magnets? Draw some artifi cial magnets and label the poles .

2. Explain the attraction and repulsion between magnetic poles.

3. Write the properties of magnets.

4. When does a magnet lose its magnetic property?

V. Write down names of substances.

Std06 Sci Eng

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