A steel tumbler, a plastic tumbler, a glass tumbler — same object, three different materials, three different feels.
Key idea
Observing Objects Around Us
Any substance used to create an object is called a material
paper, wood, cloth, glass, metal, clay.
Same object, different materials
A tumbler can be made of steel, plastic, or glass — the choice depends on the object's purpose and the material's properties.
An ancient craft
Indian pottery-making goes back 7,000–8,000 years — clay was carefully selected, cleaned, shaped, and baked into terracotta.
Key idea
How Do We Group Materials?
Arranging objects into groups based on a common property is called classification. Different people may pick different features — shape, colour, hardness — as the basis for grouping.
ClassificationThe method of arranging objects or materials into groups, based on a property they share.
Key idea
Lustrous and Non-lustrous Materials
1
Lustrous
Materials with a shiny surface — usually metals, like iron, copper, zinc, aluminium, and gold.
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2
Non-lustrous
Materials without shine — paper, wood, rubber, jute. Note: not everything shiny is a metal — some materials are polished or coated to shine.
Key idea
Hard and Soft Materials
1
Hard
Difficult to compress or scratch — e.g. stone, iron.
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2
Soft
Compresses or scratches easily — e.g. sponge, eraser. Hardness is relative: rubber is harder than sponge, but softer than iron.
Key idea
Transparent, Translucent, and Opaque
1
Transparent
You can see clearly through it — glass, water, air.
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2
Translucent
You can see through it, but not clearly — butter paper, frosted glass.
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3
Opaque
Nothing can be seen through it — wood, cardboard, metal.
Key idea
Soluble and Insoluble Materials
1
Soluble
Completely dissolves in water — sugar, salt. Even some gases, like oxygen, are soluble in water — vital for aquatic life.
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2
Insoluble
Does not dissolve in water — sand, chalk powder, sawdust.
Key idea
Mass and Volume
1
Mass
The property that tells whether an object is heavier or lighter. A heavier object has more mass. Commonly measured using a balance.
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2
Volume
The amount of space occupied by an object or substance — shown by different water levels in identical tumblers.
Key idea
What Is Matter?
Mass and volume are two properties possessed by all materials.
MatterAnything that occupies space and has mass is called matter — mass is measured in grams (g) or kilograms (kg); volume in litres (L) or millilitres (mL).
An ancient idea tooAyurveda classified matter using 20 properties (guna) in 10 opposite pairs — like heavy/light and hot/cold.
Chapter · Key terms to remember
Key Terms
Material
Any substance used to create an object.
Classification
Grouping by a shared property.
Lustrous / Non-lustrous
Shiny / not shiny.
Chapter · Key terms to remember
More Key Terms
Hard / Soft
Hard to / easy to compress or scratch.
Transparent / Opaque
Clear to see through / not at all.
Translucent
Partly, unclearly see-through.
Chapter · Key terms to remember
More Key Terms
Soluble / Insoluble
Dissolves / does not dissolve in water.
Matter
Anything with mass that occupies space.
Questions for your notebook
Write these down, then discuss
1
Visit your kitchen and observe how your parents have organised various edibles. Can you suggest a better sorting method?
2
Unscramble the letters and match with their properties: (i) T R E M A T (ii) U L S B E L O (iii) T N E R P A S N A R T (iv) E R U S T L
3
Containers used to store materials in shops and homes are usually transparent. Why?
Project as-is — students copy the questions, then the class discusses answers together.