Science Notes — Class Three

Many things happen around us, and we would like to know why they happen. Science helps us find those answers.

Have you ever wondered about...?

• Why do plants increase in size and height?
• Why does ice melt when taken out of a freezer?
• How does a whistle make sound when blown?
• Why does food rot when left for some days?
• How does a chicken egg become a chick?
• How does electricity produce light in a bulb?
• What happens to our bodies when we are sick?

We study Science to understand these and many other things that happen in our environment. Once we understand these processes, we can stop the bad ones (like food rotting) and repeat the good ones (like cooking food).

A person who uses science to explain about things or make things is called a scientist. A scientist can specialize in one of the many branches of Science. Each branch explains a particular thing in our natural world. There are three main branches of science.

1. Physics

Physics is the study of matter, energy and forces. We use electricity to operate the TV, fridge, stove, radio and lights. We learn about different energies like heat, electricity and sound, and how machines work, in Physics.

2. Chemistry

Chemistry is the study of the behaviour of materials and how they react with one another. When substances mix together to form new materials, or when they burn, we are applying Chemistry.

3. Biology

Biology is the study of living things. It is also called Life Science. In Biology, we study living things, their bodies, and their needs.

Sub-branches of Science

The three main branches also have smaller branches under them.

• Astronomy (branch of Physics) — studies the sun, moon, stars, earth and other bodies in space, using telescopes to see far away.
• Geophysics (branch of Physics) — studies the physical processes of the earth.
• Zoology (branch of Biology) — studies animals: where they live and how they interact with other living things.
• Botany (branch of Biology) — studies plants: their body structure, how they are related, where they grow, and the materials they make.
• Marine Biology (branch of Biology) — studies living things found in the ocean and other salty water, such as fish, algae, plants, fungi and bacteria.
• Paleontology (branch of Biology) — studies fossils, the remains of living things (like dinosaurs) that lived long ago.

We are usually interested to know why or how things occur in our environment. This interest is called curiosity. To understand why things happen, we use the scientific method to carry out a scientific investigation — a way of finding answers through careful observation and experiments. It has six steps.

Step 1: Problem Identification

A problem is anything you do not understand or want to know about. Identifying a problem means stating what you want to know about something.

Step 2: Hypothesis Formulation

After identifying a problem, a scientist makes an intelligent guess that tries to answer it. This guess is called a hypothesis.

Step 3: Experimentation

Next, you conduct an experiment — a systematic procedure to check whether the hypothesis is correct.

Step 4: Data Collection

We record the changes that occur by observing and measuring. We use our sense organs: eyes for seeing, nose for smelling, skin for feeling, ears for listening, and tongue for tasting.

Step 5: Data Interpretation

This means explaining the observations or results of your investigation, relating them back to the aim of the investigation.

Step 6: Conclusion

A conclusion states the findings of the experiment and whether the hypothesis was correct. If the hypothesis was wrong, the investigation is carried out again with a new hypothesis.

A scientific report is written after conducting a scientific experiment. It describes the problem and all the steps and materials used during the investigation, and helps other scientists understand what was done. A scientific report has six parts:

1. The problem statement
2. Aim or objective of the investigation
3. Materials or equipment
4. Procedure of data collection
5. Data analysis and results
6. Conclusion

The scientific process and the study of science are important for many reasons:

• It helps us understand better about different things that occur in the environment.
• It helps us find solutions to different problems affecting us.
• It motivates us to think better about why things occur in nature.
• It helps others learn about how things occur.
• It teaches us about our bodies, other living things, and diseases that affect them.
• It gives us better understanding of the earth, stars and outer space.
• It gives us knowledge about energy, machines, and how to make tools that simplify our work.