What is soil
Soil is formed by erosion that is breaking up of rocks , by the action of sun, wind and rain. It forms at the surface of land and is the “skin of the earth.” Soil is capable of supporting plant life and is vital to life on earth.
Soil contains a lot of different things; a few essential ingredients are listed below:
Sediment – Every soil contains some mixture of sediments. The three main sediments are sand, silt, and clay. The type of sediments determines a soil’s type. Ideal soils (for farming) are a mixture of the three.
Organic Matter – Soil contains a lot of partially decomposed organisms which is called organic matter. Microbes in the soil break it down to make important nutrients. Most organic matter comes from plants. This is also called Humus and is dark brown or black in color.
Minerals – There are tons of different minerals in the soil. They’re used by plants for growth. When plants die, their minerals return to the Earth.
Types of soil and properties
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
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.
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
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).
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
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;
- Fresh foods
- Cooked foods
Removing water prevents the microorganisms from growing, or digesting the food.
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.
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)
- White sugar you would find in a sugar bowl
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 :
Involves cooking the food at the boiling temperature of water ie 100 degree centigrade.
Example : Eggs , potatoes etc
A quick look at the Grade 1 lessons :
Weather and The Sky:GK questions on space
Weather and The Sky: Earth and Sky fundamentals
- 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.
- Orbits the sun
- Has sufficient mass to be round, or nearly round
- Is not a satellite (moon) of another object
A look at the grade 2 lessons :
Grade 2 science (NSO) : Animals
Animals:Domestic and Wild
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.
Before starting lets take a look at the Grade 2 lessons
Plant – Types of plants
Plants – Parts we eat
Plants : Uses of different plants
Responsible for reproduction
Colour and fragarence of flowers attract insects who act as pollinators.
Flower parts that we eat :