Kids Learning Science IV Term-II

 

4th Standard Science Term-II

Plants

Introduction

All living things need food.  Food helps them grow and perform daily activities.  We have seen animals eating their food.  But, have you ever wondered how plants get their food?  Plants produce their own food with the help of chlorophyll, a pigment present in leaves.  Humans and animals depend on plants for their food either directly or indirectly.  Let us learn more about plants in this lesson.

I. Parts of Leaf

Leaves are of different shapes and sizes and have different parts.  However, there are some basic parts that are common in most of the leaves.

Blade : The broad flat part of the leaf(Lamina).

Apex : The tip of the leaf.

Midrib : The midrib runs along the centre of the leaf.

Veins : Veins branch out form the midrib.  They are the framework of hollow tubes that carry water and minerals.

Petiole : This part joins the leaf to the main stem.

https://youtu.be/Ahx_wxndmyY

Stomata : Stomata are tiny openings or pores mostly found at the base of the leaves.  Air enters and leaves the plant through these openings.  Stomata helps the plants to breathe.  Stomata are used to exchange gases.

1. Leaf as food factory

Plants need food but they never depend on people or animals to get their food.  Most of the plants are able to make their own food through a process called photosynthesis.

Photosynthesis = Photo (light) + synthesis (make)

Photosynthesis is a process by which plants make their food using chlorophyll water and carbon dioxide in the presence of sunlight.  Let us see how this process is organized within the plants.

Water : Water is absorbed by the roots and is transported to the leaves through the tubes.

Carbon dioxide : Carbon dioxide in the air passes through stomata in the leaves.

Sunlight : A green pigment in the leaves help them to trap sunlight.  This pigment is called chlorophyll.  Most leaves are green in colour because of this green pigment

Through photosynthesis plants produce the food and release oxygen into the air.

                                           Sun light

   Water + Carbon dioxide      ➜        Food + Oxygen

                                          Chlorophyll 

As plants prepare food for themselves and also for other living things, they are called primary producers.

Without primary producers, living things are not capable of producing their own food and will not be able to live.

More to Know

In plants like cactus, leaves are modified into thorns.  Their food is produced in the green stems.

II. Classification of Plants

Plants are classified in many ways based on stems, life span, seeds, flower and colour.  In this section we will study about the classification of plants based on flower and colour (pigment).

1. Flowering and Non-flowering plants

Flower is the most important part of many plants, because it is involved in reproduction.  But some of the plants are not having flower.  These plants reproduce in different modes.  Based on this, plants can be classified into two types.

❖ Flowering plants

❖ Non-flowering pants.

Flowering plants

Plants bearing flowers are called flowering plants.  Some of them reproduce by sex cells or gametes and produce seeds.  Seeds produce new plants.  Eg - Mango, Neem, Groundnut, Paddy etc.

Non-flowering plants

Plants that can reproduce without flower are called non-flowering plants.  These plants to not produce seeds.  They reproduce by a special structure called spores.  E.g. Algae, Fungi, Fern.

2. Green and Non-green plants

The most important pigment present in plants are called chlorophyll.  Based on the colour present in the plant, they are divided into two groups.  They are green and non-green plants.

Green Plants

Plants containing green pigments are called green plants.  It looks green in colour.  They prepare their own food with the help of them.  It depends on atmosphere, light and pigment for food preparation.  Green plants are commonly called autotrophs.

E.g. Grass, Paddy, Algae etc.

Non-green plants

Plants that do not contain chlorophyll pigment and do not look green and called non-green plants.  They cannot prepare their food.  These plants depend on other organism for their food and living place.  These are commonly called heterotrophs.

Sepal : Sepals are leaves that protect the flower while it is still a bud.  Sepals are usually green or brown.

Petal : Petals are often bright coloured.  Their main job is to attract insects such as bees or butterflies, to the flower.  The insects help the flowers in the transfer of pollen grains.

Stamen : Stamen can be seen at the centre of a flower.  They contain pollen grains that help the plants to multiply.  It is the male part of a flower.

Pistil : Pistil is also seen at the centre of the flower.  The pistil uses the pollen to help the flower to become fruit.  It is the female part of a flower.

More to Know

The largest flower in the world is Rafflesia.  This rare flower is found in the rainforests of Indonesia.

Seasonal Flowers

The change in climate that occurs periodically is called seasons.

There are four general seasons - Spring, Summer, Autumn and Winter.

Most flowers bloom in a specific season.  Hence, they are called seasonal flowers.

More to Know

Firecracker flowers bloom in all seasons

Kurinji flower blooms once in 12 years 

IV. Exotic Plants

The plants that grow outside their native area either purposefully or accidentally are called exotic plants.

Most of these plants are brought to new areas for decoration purposes.  Some of them are given below.

https://youtu.be/NIHMP0nlOyQ

More to Know

Parthenium plant accidentally grow in a new native.  This plant expands its range and disturbs the cultivation areas.  The pollen of this plant is allergic in nature.  So, do not touch this plant wherever you see.

V. Plants as Food

Humans and other animals often use plants as food.  Plants which we eat are edible.  Edible parts of some plants include leaves, stems and roots.  We also eat fruits produced by plants.

Edible parts of plants

All the parts of different plants are edible, that is, we can eat them as food.

Roots as food

Many plants store excess food in their roots.  They have thick and swollen roots.  These roots are used as food.  Some of them are given below.

Stems as food

In some plants the stem stores the excess food in it.  Potato, onion and ginger are the underground stems that we eat.  Some of them are given below.

Leaves as food

Leaves of some plants are used as food.  In some plants extra food is stored in leaves.  We eat the leaves of some plants like cabbage.  Some of the leaves used as food are given below.

Flowers as food

Flowers are the part of a plant.  Many flowers are used as food.  Some of them are given below.

Fruits as food

Many fruits are used as food.  Fruits are rich in vitamins and minerals.  They keep us healthy.  All fruits can be eaten raw.

Grains as food

Grains of pulses, cereals and pods are the commonly eaten seeds.  They are the rich sources of carbohydrates and proteins.

More to Know

Trees are the longest living organism on earth.  Bamboo plants can grow upto 90 cm in a day.

Kids Learning Science IV Term-II

 
4th Standard Science Term-II

Water

Learning Objectives

✤ After learning this lesson, students will be able to :

✤ understand the change of states in water.

✤ describe water cycle.

✤ explain the importance of water cycle.

✤ summarise rainwater harvesting and its uses.

Introduction

    Water is the most abundant and precious resource on the Earth.  It is found in oceans, seas, rivers, streams, lakes, ponds and under the ground.  All living things need water to live and to do many other activities.  We have already learnt about this in your previous class.  Let us learn more about water in this lesson.

Change of States in water

Water occurs naturally in three forms :

ice, water and water vapour.

    These forms are also called states of water.  Ice is in solid form, water is in liquid form and water vapour is in gaseous form.

    These states occur naturally because of temperature changes.  Water becomes ice in cold regions, remains as water in oceans/rivers and becomes water vapour due to the heat of the Sun.

More to know

Human body consists of 75% of water by mass.

SOLID STATE (Ice)

    Ice is a solid form of water.  At temperature below 00C water becomes ice.  This process is called freezing.

                                Cooling

                    Water    →   Ice     

                                below 00C

LIQUID STATE (Water)

    Water in liquid state is available in water bodies such as oceans, river, waterfalls etc.

GASEOUS STATE (Water vapour )

    Water becomes water vapour as the temperature increases due to heat. Heating forms a white mist of extremely small water droplets in the air known as water vapour. 

                           Heating

              Water    →   Water vapour

                            1000C

II. Water Cycle 

    In nature, water keeps changing its state.  Let us see how this happens. Due to the Sun's heat, water in oceans and rivers changes into water vapour and rises up. 

    Water changing into water vapour on heating is called evaporation.  The water vapour, when comes into contact with cool air, becomes water droplets. This is called condensation. The water droplets combine to form clouds. The water droplets continue to combine, and they become big and heavy. These water droplets then fall down as rain. This is called precipitation. In colder places, combined water droplets come down as snow, sleet or hail. This continuous change of water from one state to another in nature is called water cycle. 

    The continuous cycle through which water is circulated by different processes like evaporation, condensation and precipitation is called water cycle.

 

More to know 

Each day, we lose a little more than a cup of water when we exhale. 

Importance of Water Cycle 

• To improve the availability of ground water. 
• To control the Earth's temperature.
• To provide water to plants and animals especially humans. 
• To recycle the Earth's supply of water constantly. 

Do You Know 

73% of our brain's mass consists of water. The Antartic region has about 70% of the worlds fresh water. 

III. Rainwater Harvesting

    'Rainwater harvesting' is the process of collecting and storing rainwater for future use. Rainwater can be collected in natural reservoirs or artificial tanks. Roof top harvesting is also type of rain water harvesting. The rainwater on the top of the building is collected and passed into the ground through pipes. Water passing through the pipes enters the pit which consists of gravels and coarse sand. As it passes impurities are filtered and it is stored as ground water. 

More to Know 

H2 O is the chemical formula of water.

Do You Know 

One inch of rainfall on a 2,000 sq.ft. roof is equal to 4,800 litres of water. 

Benefits of Rainwater Harvesting 

• It increases the ground water level. 
• It can be used for agriculture. 
• It increases the availability of water for living things. 

Rain water harvesting is the only way to conserve rain water.

More to Know 

• Rainwater harvesting was launched in the year 2001 by the Tamil Nadu government. 
• Tamil Nadu is the first Indian state which made rainwater harvesting mandatory.  

  

Kids Learning Science IV Term-II

 

4th Standard Science Term-II

Food

Learning Objectives

After learning this lesson, students will be able to :

* differentiate between raw and cooked food items.

* understand different methods of cooking. 

* describe different types of cooking utensils.

* identify hygienic food and food to be consumed during illness.

* insist the importance of not wasting food.

Introduction

Food is one of the basic needs of life.  We get energy for all our activities from food.  Food obtained from nature provides all the nutrients to our body.  But seeing the advertisement, we are attracted towards junk food.  In this lesson, we will study about food items that are good for our health, cooking methods and the importance of not wasting food.

I. Food

In our daily life, we depend on plants and animals for our food.  Some can be eaten raw but most of them need to be cooked.  Let's see which food items can be eaten raw and which one needs cooking.

1. Raw Food (Uncooked Food)

Food that we can eat directly without cooking is called raw food.

We can eat fruits, some vegetables, tubers and nuts in the raw form.  Some pulses and cereals and also eaten as raw food.  All raw food must be washed with clean water before eating.  Some of the raw food items are given below.

Let us Do

Arrange some fruits, vegetables, nuts and tubers on the table and ask each student to pick one food item.  Based on what on what food item they choose, ask them to join in the same kind of food item.

Let us Make

Shall we make some salad?

Collect some raw food items available in your locality.  Clean them with fresh water, cut them into small pieces (keep the nuts whole), put them in a bowl then add salt and pepper and mix it well.  Enjoy your tasty salad!

2. Cooked Food

We cannot eat all the food items in raw form.  Food that needs to be processed using heat before it can be eaten is called cooked food.

Why should we cook food?

• Cooked food is easy to digest.
• Cooking softens the food materials.
• Cooking kills germs.
• Cooking adds taste and flavour to food.

II. Cooking Methods and Habits

Think and Answer

Children, look at the menu card given here.  You can see food ites on this menu.  Do you think all these items are cooked in the same way?

Some of the cooking methods practiced commonly are given below.

Boiling : It is a method of cooking food by immersing in boiling water, so that the food becomes soft.  Example : Rice, Egg.

Steaming : It is a method of cooking food using steam generated from boiling water in a pan.

Example : Idli, Idiyappam.

Pressure cooking : It is a method of cooking food in a pressure cooker.  

Example : Rice, Dhal.

Roasting : It is a method of cooking food by heating it on a tawa or frying pan without covering it.  Example : Groundnuts, Cashewnut.

Frying : It is a method of cooking food in hot oil.  

Example : Chips, Poori.

Cooking Habits

• Wash your hands with soap before cooking.
• Wash vegetables and fruits before cutting.
• Wash cooking vessels and knives.
• Don't cook food for a long time because it destroys the nutrients present in the food.
• Don't use the same oil many time for cooking food.
• Using the food items after their expiry date is not good for health.

III. Cooking Utensils

Utensils are in different shapes and sizes.  We use specific utensils for each cooking method.  Clay pots were used earlier.  Stainless steel and aluminum vessels are now generally used for cooking.

Cooking in Clay Pot

Clay pots are well-suited for all types of cooking.  Cooking in clay pots improves the quality and taste of food and also retains the nutrients.  The natural insulation properties of clay cause heat and moisture to balance and circulate throughout the pot and keep the nutrients unharmed and prevent the dish from burning.

Benefits of claypot cooking

• Easy to digest.
• Preserves the nutrients.
• Needs less oil for cooking.
• Adds flavour to the dish.
• Keeps the food warm for a long time.
• Keeps the food from becoming stale soon
• Alkaline property in the pot neutralizes the acidic property in the food.

Solar Cooker

It is an appliance which is used to cook food using sunlight.  It saves fuel and reduces air pollution.  

IV. Meal - time Hygiene

Think and Answer

Look at the pictures given below.  Which one is good for health? Why?

Meal - time hygiene includes ways to make sure that we do not get sick because of the way we eat or make food.  Some of the hygienic ways of taking food are given below.

• Always cover food to protect them from dust and insects.
• Eat fresh food always.
• Avoid taking food that is too cold or too hot.
• Avoid fast food and fried food.
• Always wash your hands with soap before and after eating.

Let us Discuss

Here is Nandini's lunch box.

a. Are all the items in the box healthy?

b. Suggest her to remove one food which is not healthy and add one food which is healthy.  Give reasons for change.

V. Food during Illness

Think and Answer

When you are sick, what kind of food your mother serves you?

When we are sick, we should avoid food items that are fried in oil.  We should take energy - giving, easily digestible food.  Some of them are given below.

• Porridge of rice or cereals.
• Fruit juice, tender coconut.
• Steamed foods like idly.

Let us Do

Note to the teacher

Make small paper rolls, each having a food item's name written on it.  Put all of them on a table.  Make two big circles on the floor.  Name one circle 'MUST AVOID DURING ILLNESS' and another circle 'MUST TAKE DURING ILLNESS'.  Ask children to take one roll each and stand in the appropriate circle after reading the name on the roll.

VI. Food Wastage

Think and Answer 

1. Do you usually eat your lunch without wasting anything? If you say no why do you waste?
2. Can you suggest a few ways to reduce wasting food in your school and house?

We should not waste food.  Food that is not eaten is called leftover food.  This food is discarded as waste.  Following are the simple ways to avoid food wastage.

• Take what you can eat and eat what you take.
• Share the excess food.
• Give the excess food to the needy.

Do you Know

One third of the food produced in the world is wasted.  It is a total of 1.2 lakh crore tonnes per year.  (1 ton = 1000 kg)

Food Preservation

We can preserve the food for long time by using the following methods.

Picking : Mixing fruits and vegetables with oil and salt.

Example : Pickle.

Refrigerating : Keeping food in the refrigerators (fridge) to preserve them for a short time.

Example : Fruits, Vegetables.

Drying : Removing the water content  of the food.

Example : Fish, Red chillies.

Canning : Storing food in airtight containers.

Example : Jam.

Do you Know

World Hunger Day - May 28.

Let us Do

Make students list out all the food items wasted in their home for one week.  Make them discuss what they saw and what they can do to reduce waste.