Introduction To Science - Session 2

Matter is everything around us. It is the air we breathe, the water we drink, and the food we eat. Matter is anything that has mass and takes up space. It can be as small as an atom or as large as a planet. Understanding matter is essential to understanding the world we live in. Without matter, we would not exist. This because we are also matter.

Matter can exist in three main states. These states are solid, liquid, and gas. These states are determined by the arrangement of particles within the substance. Solids are made up of tightly packed particles. An example of solid is ice. Liquids are made up of particles that are more spread than in solids. These particles are able to move around each other. Water is an example of a liquid. Gases have particles that are very far apart. These particles move freely until they bump into other particles. An example of gas is water vapors.

You might have seen that when you heat ice, it is converted into liquid water. In this process a solid is converted into liquid. We can say that matter has changed state from solid to liquid. This process is called melting. When we cool-down the water it is converted into solid ice. This process is called freezing.

When a liquid is heated, it can change its state into a gas. This process is called melting. For example, when we heat the liquid water, it is changed into steam. Steam is water in the form of gas. As we can see, these simple processes that happen in our daily life involve science.

Have you ever wondered why objects drop to the ground? Why do planets stay in their orbit? This is due to force. force is an invisible push or pull that influence the motion of an object. force is everywhere around us. Objects drop to the ground due to the force of gravity of earth. In the same way, planets stay in orbits due to the force of gravity of sun.

When we start rolling a ball on ground, after some time it stops rolling. Do you know why it stops rolling? It is due to the force of friction. Force of friction keeps objects in place and slows them down. Force of friction acts opposite to direction of motion of ball.

Energy is what makes things happen. It is like the fuel that powers everything around us. When we turn on a light, energy is what makes the light shine. When we run or jump, energy is what helps our muscles move. Energy can come in different forms, such as light, heat, and electricity. It can change from one form to another. However it can't be created or destroyed. For example when we turn on a light bulb, the energy which is in the form of electricity is converted into energy in the form of light.

We eat fruits and vegetables for energy. But where do these fruits and vegetables come from? Ofcourse plants prepare these fruits and vegetables for us. But how do plants prepare their food? Plants prepare their food by a process called photosynthesis. Photosynthesis is the process by which plants prepare food with the help of sunlight, water and carbon dioxide. Plants absorb water through roots from soil.

We know that animals such as sheeps, cattle and goat eat plants as food. Such animals that rely on plants for fulfilling their energy requirements, are called herbivores. Herbivores do not eat any food other than plants. Some other examples of herbivores are rabbit, cow, and elephant.

Carnivores are animals that eat other animals. They have special features like sharp teeth and strong bodies that help them catch and eat other animals. Some examples of carnivores are lions, wolves, and sharks. Carnivores are important because they help control the population of other animals and keep the population balanced.

Omnivores are animals that eat both plants and other animals. They have a more flexible diet compared to carnivores or herbivores. Examples of omnivores include humans, bears, and raccoons. They have different types of teeth that allow them to eat both meat and plants. Omnivores have an important role in nature because they can adapt to different food sources.

Decomposers are the organisms that breakdown dead plants, animals, and waste into smaller pieces. They release helpful substances that make their way into the soil or water. These substances help plants and other living things grow. Decomposers clean up the environment by getting rid of waste and keeping things balanced in nature. An example of decomposers is bacteria. Bacteria are small microorganisms that can not be seen with naked eye.

We have studied that different types of organisms likeherbivores, carnivores, omnivores and decomposers are dependent on each other. They help keep the environment in a balanced state. For example if there are no carnivores, then number of hervivores will increase. Increased number of herbivores will eat all plants. This will cause a disturbance in our environment.

A food-chain demonstrates the relationship between different organisms and how they depend on each other for survival. In a food-chain, each living thing is connected to another through what they eat and what eats them. It starts with a producer. Producer is usually a plant which can make its own food using sunlight. The producer is then eaten by a consumer. Consumer is an animal that eats plants or other animals. This consumer might in turn be eaten by another consumer. This creates a chain of who eats whom.

For example, grass is a producer because it can make its own food through photosynthesis. A grasshopper comes along and eats the grass. So the grasshopper is a primary consumer. Then a frog eats the grasshopper. Therefore the frog is a secondary consumer. Frog is then eaten by a snake. After that a bird such as an eagle eats the snake. After the death of the eagle the bacteria and fungi decompose eagle. The decomposed product of the eagle is again used by the producer which is grass. In this way the cycle continues.