Grade 3 Science (NSO) : Earth and Universe

A look at the previous lessons on earth and universe :

Grade 2 Science (NSO) : Earth and universe

Weather and The Sky: Earth and Sky fundamentals

Earth’s Revolution

The motion around the sun along its orbit is called a revolution . The amount of time it takes for a single trip around the sun is called a period of revolution. The period for the Earth to revolve around the sun is 365.24 days or one year. The .24 days is why every four years February has 29 days.

There are 4 seasons in an year .In Autumn and Spring the northern and southern hemispheres are tilted equally toward the sun.In Summer the Earth is on the other side of the sun and the northern hemisphere is tilted  toward the sun and gets better sun rays. In winter the northern hemisphere is tilted away from the sun. That’s how we get seasons.

Earth’s orbit around the sun is slightly elliptical, Earth is actually slightly closer to the sun in the winter than it is in the summer.It is the tilt of Earth’s axis that causes the seasons.

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Grade 3 science (NSO) : Human body part 3

Links to part 1 and part 2 of the human body

Grade 3 Science (NSO) : Human body part 1

Grade 3 Science(NSO) : Human body part 2

Nervous system

This system controls all our actions, sense of feelings and thinking is called Nervous system.The nervous system is a complex collection of nerves and specialized cells known as neurons that transmit signals between different parts of the body. It is essentially the body’s electrical wiring.

  • It consists of the brain, spinal cord, sensory organs, and all of the nerves that connect these organs with the rest of the body
  • Brain is the most vital organ of our body
  • It sends and receives messages to and from all parts of the body through nerves
  • Spinal chord is the bundle of nerves that runs up and down the center of the back; connects the brain to the nerves; carries signals between the brain and other parts of the body
  • The brain and spinal cord form the control center known as the central nervous system (CNS).

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Grade 3 Science (NSO) : Food part 3 – Preservation of food

Food Decay and Preservation

Bacteria and fungi are the main groups of  decomposer organisms. Food decay is also known as food spoilage.

Bacteria and fungi need Food , Warmth and Moisture to grow.

There are several ways to stop or slow down the decay of foods. This is known as Food Preservation.

 

Food preservation methods

 Freezing

Bacteria cannot reproduce at low temperatures.

Bacteria and fungi need warmth to grow. In low temperatures they stop growing.

Following is the list of food preserved by freezing;

  • Meat
  • Fish
  • Fruits
  • Vegetables
  • Fresh foods
  • Cooked foods

Drying

Removing water prevents the microorganisms from growing, or digesting the food.

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Grade 3 Science (NSO) : Food Part 1 – Food Types

A look at the grade 2 lesson

Grade 2 Science(NSO) : Food

Food can be divided into three types

Energy giving food

Give us energy to work. They contain carbohydrate and fats.

Carbohydrates

They are found in foods like rice, pasta, cassava, yam etc. when starchy foods are eaten and digested, simple sugars like glucose are obtained. It is this glucose that the body uses for energy.

There are two major types of carbohydrates:

1. Simple carbohydrates (Sugar)

  • Fruits
  • Milk
  • White sugar you would find in a sugar bowl
  • Chocolates

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Grade 3 Science (NSO) : Food Part 2 – Methods of Cooking

Cooking of food

Cooking improves the flavor of food and also makes the food easier to chew and more digestible. Micro oirganisms present in the food are killed during cooking which makes the food safer to consume. Various methods of cooking are listed below :

Boiling

Involves cooking the food at the boiling temperature of water ie 100 degree centigrade.

Example : Eggs , potatoes etc

Advantages :

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Grade 2 Science (NSO) : Earth and universe

A quick look at the Grade 1 lessons :

Weather and The Sky:GK questions on space

Weather and The Sky: Earth and Sky fundamentals

 Solar system

Sun :

  • It is a star.
  • It gives us heat and light
  • It is the main source of energy on the earth
  • Eight planets and many heavenly bodies revolve around the sun.

Planets :

  • Orbits the sun
  • Has sufficient mass to be round, or nearly round
  • Is not a satellite (moon) of another object

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Grade 3 Science (NSO) : Birds

Bird, a warm-blooded vertebrate that lays eggs and has feathers and wings.

Type of beaks

 

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Grade 3 Science (NSO) : Animals

A look at the grade 2 lessons :

Animals:Lifecycle

Animals:Animal homes

Grade 2 science (NSO) : Animals

Animals:Baby names

Animals:Domestic and Wild

Animals: Classification

Animals:Facts about animals

Animals and the way they eat

Herbivores : Animals like cows , buffaloes , sheep etc., that eat plants.
Carnivores : Animals like lions, tigers, etc., that prey on and eat other animals.
Omnivores : Animals like bears, crows etc., that eat both plants and animals.
Scavengers : Animals like vultures and jackals that eat dead and left over animals generally preyed on by carnivores.

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Grade 3 Science(NSO):Plants : Stem

Stem

Stems are the aboveground structures that bear the plant’s leaves and flowers. The stem provides a host of services to the plant:

  • It provides a pathway for transporting water up to the leaves, and moving the sugars produced in the leaves down to nourish the roots.
  • It acts as a sturdy mast to hold up the leaves and help orient them for maximum exposure to sunlight.
  • It can act as a storage site for carbohydrates.

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Grade3 Science (NSO) : Plants :Roots

Plants :Roots

Root

Root is the underground part of the plants body. It fixes the plant within the soil and absorbs water and mineral nutrients from the soil. It also stores excess food.

Function of roots

  • Roots attach the plant body to the ground. It provides support to the plant and helps in holding the plant firmly in the ground.
  • Root hairs of the plant absorb water and mineral from the soil and pass it to the stem.
  • Some roots like carrot, radish etc. store food.
  • Root bind the soil which otherwise may be blown away by wind or washed away by water. Root prevents soil erosion.

Types of roots

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