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) : 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) : 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) : Flower, fruit and seed

Before starting lets take a look at the Grade 2 lessons

Plant – Types of plants

Plants – Parts we eat

Plants: Fruits

Plants : Uses of different plants

Flower

Responsible for reproduction

Colour and fragarence of flowers attract insects who act as pollinators.

Flower parts that we eat :

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