Exploration: Entering the World of Secondary Science (RBSE Class 9 · Science)
Why is the sky blue? Why does ice float? Why do heavy and light objects fall together? Science begins not with answers but with a question — and the courage to go and find out. This opening chapter is an invitation: to look closely, ask "why", and learn the disciplined way scientists turn curiosity into knowledge.
RBSE note (2026-27). Class 9 uses the new NCF (Curiosity) Science textbook. This is its introductory chapter, setting up the way of thinking used throughout the year. BSER (Ajmer) sets the exam.
1. What is science?
Science is an organised way of understanding the natural world through observation, questioning, experiment and reasoning. It is not just a collection of facts — it is a method of finding reliable answers and a willingness to change our ideas when the evidence says so.
Two attitudes drive it:
- Curiosity — noticing things and asking why and how.
- Scepticism — not accepting a claim until it is supported by evidence.
2. The scientific method
Scientists follow a broad, repeatable process (not always in a fixed order):
- Observation — notice something in nature.
- Question — ask a clear, testable question about it.
- Hypothesis — propose a possible explanation (a smart, testable guess).
- Experiment — design a fair test, changing one factor at a time (the variable) while keeping others constant.
- Data & analysis — record measurements carefully and look for patterns.
- Conclusion — decide whether the evidence supports the hypothesis.
- Communicate & repeat — share results so others can verify them.
A key idea: a good experiment is a fair test — you change only one thing and use a control for comparison. Results must be reproducible by others.
3. Observation vs inference
- An observation is what you directly notice with your senses or instruments (e.g. "the liquid turned blue").
- An inference is a conclusion you draw from observations (e.g. "a chemical reaction occurred").
Keeping the two apart is a core scientific skill — many wrong conclusions come from mixing them up.
4. Measurement and SI units
Science depends on measurement — turning observations into numbers. To compare results worldwide, scientists use the International System of Units (SI):
| Quantity | SI unit | Symbol |
|---|---|---|
| Length | metre | m |
| Mass | kilogram | kg |
| Time | second | s |
| Temperature | kelvin | K |
| Electric current | ampere | A |
Every measurement has a magnitude and a unit (e.g. 5 m). Use appropriate instruments (ruler, balance, measuring cylinder, thermometer) and record readings honestly, including their uncertainty.
5. Working safely and honestly
Science must be done safely and ethically:
- Follow lab safety rules — handle chemicals, glassware and flames with care; wear protection where needed.
- Record data honestly — never fake or "adjust" results to fit the hypothesis.
- Respect living things and the environment during investigations.
6. The branches of science
Science is vast, so it is divided for study:
- Physics — matter, energy, motion, forces, light, electricity.
- Chemistry — substances, their properties and reactions.
- Biology — living organisms and life processes.
In real problems these overlap (e.g. how a plant makes food is chemistry and biology). Class 9 will draw on all three.
7. Quick recap
- Science = understanding nature through observation, questioning, experiment and reasoning.
- The scientific method: observe → question → hypothesis → fair-test experiment → data → conclusion → communicate/verify.
- Distinguish observation (what you see) from inference (what you conclude).
- Measure using SI units (metre, kilogram, second, kelvin, ampere); every measurement has magnitude + unit.
- Work safely and honestly; results must be reproducible.
- Main branches: physics, chemistry, biology — often overlapping.
