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Class 8 Science NCERT Notes – Chapter 1: Exploring the Investigative World of Science PDF
ByAKS
1. Introduction – Probe and Ponder
- The chapter starts with questions meant to inspire curiosity, such as:
- Why is one side of a puri thinner than the other?
- Are there more grains of sand in the world or more stars in our galaxy?
- Why does nature create such variety in plants and animals?
- Curiosity is the starting point for all scientific exploration.
2. The Journey of Curiosity in Science
- Grade 6: Science begins with wonder, asking “Why?” and “How?” about everyday phenomena.
- Grade 7: Science is evolving; every answer leads to more questions and deeper exploration.
- Grade 8: Enter the Investigative World of Science:
- Focus on investigation, not just memorizing facts.
- Learn how to ask focused questions, design simple experiments, and use observations to build a better understanding.
3. How Investigation Works in Science
- Science is not just about collecting facts but learning how to find them yourself.
- Investigation involves:
- Asking clear, targeted questions.
- Designing and performing experiments.
- Observing carefully and explaining your findings.
- Real-life science examples:
- Why does dough rise?
- Is the Earth getting warmer?
4. What Will You Learn? (Chapter Preview)
A. Microbes and Our Body
- Begin with small things — microbes in a drop of water.
- Helpful microbes: Digestion, medicine production.
- Harmful microbes: Cause infections.
- Health: The role of food, exercise, medicines, and vaccines.
B. Electricity and Forces
- Everyday use of electric current (heating and magnetic effects).
- Introduction to forces:
- How forces make things move, stop, or change direction.
- How forces result in pressure, influencing winds and cyclones.
C. Materials and Particles
- Everything is made from tiny particles.
- Solids: Particles tightly packed and fixed.
- Gases: Particles move freely.
- Classification:
- Elements: Pure substances
- Compounds: Two or more elements bonded together
- Mixtures: Combos that can be separated physically
- Understanding solutions: How substances (like sugar) dissolve.
D. Light and Mirrors
- Study of reflection and refraction:
- Light bouncing off mirrors (flat and curved).
- Light bending through lenses.
- Everyday examples: Spoons, eyeglasses.
- All surfaces reflect — even rough ones and the Moon.
- Phases of the Moon: Linked to Earth’s movement and calendars.
E. Nature and Ecosystems
- Life depends on relationships among air, water, sunlight, and organisms.
- All living things are part of ecosystems.
- Calendars and patterns of nature depend on cycles of the Sun and Moon.
F. Earth’s Balance and Climate
- Earth is “just right” for life: distance from the Sun, liquid water, oxygen-rich atmosphere.
- Human activities can disturb Earth’s temperature, affecting climate.
- Science is necessary to study problems and find solutions.
5. Scientific Thinking Example: The Puri Experiment
A. Everyday Observation
- Question: Why does a puri puff up, and why is one side thinner?
- Science is everywhere — even in your kitchen!
B. Designing an Experiment
- Variables you can change or control:
- Thickness and size of dough.
- Type of flour (atta, maida).
- Temperature of oil.
- How you put the puri in oil.
- What can you observe or measure:
- Does the puri puff up (yes/no)?
- Time taken to puff (seconds).
- Is the thinner side always present with thicker dough?
C. Conducting & Recording
- Change only one thing at a time for a fair test.
- Use dough of same thickness, same method every time.
- Keep notes of:
- Oil splatter, smell, smoke.
- Results and observations.
D. Further Questions
- Does dough freshness affect puffing?
- What happens if you prick a hole in the puri before frying?
E. Key Scientific Principles
- Controlled experiments: One variable changes, all else constant.
- Observation is key: Record everything.
- New questions arise from results.
- Some everyday phenomena are still not fully understood.
6. Big Ideas to Remember
- Science is not limited to labs — it lives in kitchens, gardens, and everywhere.
- Asking questions, observing, and experimenting lead to discovery.
- Careful, systematic investigation and curiosity drive progress.
- We are part of solutions for challenges like climate change.
7. How to Think Like a Scientist
- Start with curiosity and simple observations.
- Ask, “What happens if…?”
- Plan and conduct experiments.
- Always record and analyze your results.
- Use evidence to explain and explore further questions.
Happy Investigating!
Use curiosity and the investigative approach to explore science in your daily life.