The Wonderful World of Science — NCERT Solutions, AI Tutor & Practice

Understand: Science is a way of understanding the world around us.

Explain:

• Science is the systematic study of the natural world through observation, questioning, and experimentation.
• It helps us understand why and how things happen—for example, why the sky is blue or how plants make food.
• Science is not just a collection of facts; it is a process of asking questions and finding answers through evidence.

Conclude: Science is both a body of knowledge and a method of exploring nature by observing, questioning, and testing ideas.

The general steps in the scientific method are:

1. Observation – Notice something interesting in nature.
2. Question – Ask why or how it happens.
3. Hypothesis – Make a possible guess or explanation.
4. Experiment – Test the guess by doing activities.
5. Analysis – Study the results collected.
6. Conclusion – Decide whether the guess was correct.

Note: If the conclusion does not match, the scientist forms a new hypothesis and tries again.

Everyday examples of science:

1. Cooking food – Heat changes raw food into cooked food (a chemical change).
2. Switching on a fan or light – Electricity makes machines work.
3. Rain and clouds – Water evaporates, forms clouds, and falls back as rain (the water cycle).

Other examples: riding a bicycle (motion and balance), a plant growing towards sunlight, and digestion of the food we eat.

Conclusion: Science is present in almost every activity we do each day.

Understand: Curiosity means the strong desire to know or learn something.

Analyze:

• Curiosity makes us ask questions about things we see around us.
• These questions lead scientists to investigate and find answers.
• Many great discoveries began with a simple curious question, such as why does an apple fall down?

Conclude: Curiosity is the starting point of all science—without asking questions, we would never discover new things.

Four branches of science:

| Branch | What it studies | |--------|-----------------| | Biology | Living things—plants, animals, humans | | Physics | Matter, energy, motion, and forces | | Chemistry | Substances, their properties and changes | | Astronomy | Stars, planets, and outer space |

Conclusion: Science is divided into branches so that different kinds of things in nature can be studied in detail.

Understand: Science has greatly changed how we travel and share information.

Transport examples:

• Cars, buses, trains, aeroplanes let us travel long distances quickly.
• Earlier people walked or used animals like horses and bullocks.

Communication examples:

• Telephones, mobile phones, and the internet help us talk to anyone instantly.
• Earlier, people sent letters that took many days to arrive.

Conclude: Thanks to science, travel and communication have become fast, easy, and comfortable.

Observation: Plants near the sunny window grow taller than those in the dark corner.

Scientific question: Does the amount of sunlight affect how tall a plant grows?

Hypothesis: Plants that receive more sunlight grow taller than plants that receive less sunlight.

Next step: This hypothesis can be tested by growing similar plants in different amounts of light and measuring their heights over time.

Conclusion: From an ordinary observation, a testable scientific question and hypothesis can be formed.

Understand: Science keeps growing over time.

Analyze:

• Every answer in science often leads to new questions.
• New tools and technology let scientists discover things not known before.
• Old ideas are sometimes corrected or improved when better evidence is found.

Example: Once people thought the Earth was the centre of the universe; later observations proved this wrong.

Conclude: Because there is always more to learn and improve, science is a continuous, ever-growing process that never really ends.

Understand: Science plays a big role in keeping people healthy.

Ways science helps healthcare:

1. Medicines cure diseases and reduce pain.
2. Vaccines protect us from diseases like polio and measles.
3. Machines such as X-ray and scanning machines help doctors find illnesses.
4. Surgery and treatments have become safer and more successful.

Conclude: Because of science, many diseases can now be prevented and cured, helping people live longer and healthier lives.

Understand: Many everyday objects work because of scientific principles.

Example 1 – Electric fan:

• It works using electricity, which turns a motor.
• The spinning blades push air, giving us a cooling breeze.

Example 2 – Blackboard and chalk:

• Chalk leaves a mark because tiny particles rub off onto the rough board surface.
• This is a simple example of friction between two surfaces.

Conclude: Even simple classroom objects work because of scientific ideas like electricity and friction.

Understand: A scientific attitude means thinking carefully and honestly like a scientist.

Two ways to develop it:

1. Ask questions – Do not accept things blindly; ask why and how they happen.
2. Test and observe – Check facts by observing and doing simple experiments before believing them.

Additional habits: being open to new ideas, recording observations honestly, and not fearing to make mistakes.

Conclude: By questioning and testing rather than blindly believing, we build a scientific attitude in everyday life.

Answers:

(a) observation

(b) hypothesis

(c) biology

Explanation:

• Observation is carefully noticing details in nature.
• A hypothesis is a testable guess made before doing an experiment.
• Biology is the study of all living organisms.