class 7 chapter-1 sub- science

on

 

Science as Exploration and Questioning (Notes)

🔍 What is Science?

Science is a way of understanding the world by:

  • Observing things 👀
  • Asking questions ❓
  • Doing experiments 🧪
  • Finding answers logically 🧠                       

Science as Exploration

  • Exploration means discovering new things.
  • Scientists explore:
    • Nature 🌳
    • Space 🌌
    • Human body 🧍
    • Technology 💻

👉 Example:

  • Discovering planets
  • Studying plants and animals
  • Finding new medicines

➡️ Science helps us know what we didn’t know before.

❓ Science as Questioning

Science always begins with a question.

Examples of Questions:

  • Why is the sky blue? 🌤️
  • How do plants grow? 🌱
  • Why do objects fall on the ground? 🍎

👉 Asking questions leads to new discoveries.

🔬 Scientific Thinking Process

  1. Observation – Notice something
  2. Question – Ask why/how
  3. Hypothesis – Make a guess
  4. Experiment – Test it
  5. Conclusion – Find the answer

🧠 Importance of Questioning

  • Helps in learning deeply
  • Develops curiosity
  • Improves problem-solving skills
  • Leads to new inventions

📘 1. Properties of Materials

🔍 What are Materials?

Materials are the substances from which objects are made.
👉 Example: wood, metal, plastic, glass

⚙️ Properties of Materials

Properties help us identify and use materials correctly.

1. Appearance 👀

  • Some materials are shiny (lustrous) → gold, silver
  • Some are dull → wood, plastic

2. Hardness 💪

  • Hard materials → cannot be scratched easily (iron)
  • Soft materials → can be easily scratched (rubber, clay)

3. Solubility in Water 💧

  • Soluble → dissolve in water (salt, sugar)
  • Insoluble → do not dissolve (sand, oil)

4. Float or Sink 🌊

  • Float → wood, cork
  • Sink → stone, iron

5. Transparency 🌈

  • Transparent → we can see through (glass)
  • Translucent → partially visible (butter paper)
  • Opaque → cannot see through (wood)

6. Conductivity ⚡

  • Conductors → allow heat/electricity (metals)
  • Insulators → do not allow (plastic, rubber)

💡 Importance

  • Helps us choose the right material for different uses
    👉 Example:
  • Cooking utensils → metal (good conductor)
  • Electric wires → copper (conducts electricity)

🔄 2. Reversible and Irreversible Changes

🔁 What is a Change?

A change is any alteration in shape, size, or state of a material.

🔄 Reversible Changes

Changes that can be undone or reversed.

Examples:

  • Melting of ice ❄️ → water → ice again
  • Stretching a rubber band
  • Folding paper

👉 Original form can be brought back.

🚫 Irreversible Changes

Changes that cannot be undone.

Examples:

  • Burning paper 🔥
  • Cooking food 🍳
  • Rusting of iron

👉 Original form cannot be obtained again.


Comments

Post a Comment