Big Ideas
- Object vs Material: Objects (bottle, table) are made from materials (plastic, glass, wood).
- Why group? Grouping (classification) by common properties makes study & choice easier and logical.
- Key properties to compare: Appearance (lustre), hardness/softness, see-through ability (transparent/translucent/opaque), solubility in water, mass (heaviness) and volume (space).
💡 Memory Hook – "LAHSTeM-V"
Lustre, Appearance, Hard/Soft, See-through, Test in water (soluble/insoluble), Mass, Volume.
Spot & List (Warm-up)
- Look around your room/class and note object → material(s) pairs (e.g., Pen → plastic body + metal clip + ink).
- One object can use many materials; one material can make many objects.
Choosing Materials for Purpose
Examples
- Tumbler must hold water: suitable → steel, glass, plastic; not suitable → cloth, paper
- Sports balls differ by material & bounce (cricket vs tennis vs hand-exercise ball)
- Pens/utensils/furniture often mix materials to combine strengths
🔎 Think like a maker
First write required properties (e.g., "must be waterproof, strong, light"), then pick the material.
Properties of Materials (with quick checks)
A) Appearance & Lustre
Lustrous (shiny)
- • Usually metals—iron, copper, aluminium, zinc, gold
- • Metals may lose shine due to air/moisture
- • Freshly cut surfaces show lustre
Non-lustrous
- • Paper, wood, rubber, jute
- • Caution: Polished/coated plastics can "look shiny" but aren't metals
B) Hard vs Soft (relative!)
Hard
Difficult to scratch/compress (stone, iron)
Soft
Easy to scratch/compress (eraser, sponge)
Relative: rubber is harder than sponge but softer than iron.
Try: Scratch test with a key on wood/chalk/metal & compare.
C) See-through ability
Transparent
See clearly (glass, clean water, air, window glass)
Translucent
See blurred (butter paper, frosted glass)
Opaque
Cannot see through (wood, cardboard, metals)
Scene check: Child looking through a glass window (transparent) vs wooden door (opaque).
D) Solubility in Water
Soluble
- • Sugar, salt disappear (dissolve)
- • Liquids: Some mix (vinegar–water)
- • Gases: Oxygen dissolves in water—vital for aquatic life
Insoluble
- • Sand, sawdust, chalk powder stay visible even after stirring
- • Liquids: Some separate (oil–water)
🍹 Health note (ORS)
If packets aren't available, mix 6 level teaspoons sugar + ½ teaspoon salt in 1 L boiled & cooled water.
E) Heaviness → Mass
Heavier cup has more mass (use a balance to compare sand/water/pebbles).
In daily talk "weight" is used, but you'll learn mass vs weight later.
F) Space → Volume
- • Same tumbler, different water levels → different volume of water
- • Common units on bottles: mL, L (e.g., 500 mL)
- • Notation rules: write a space between number & unit (e.g., 500 mL)
What is Matter?
Anything that occupies space (volume) and has mass is matter.
Mass Units
- • Gram (g), kilogram (kg)
- • kg is SI unit of mass
Volume Units
- • Litre (L), millilitre (mL)
- • SI volume: m³ (1 m³ = 1000 L)
Write with correct symbols and spacing: 7 kg, 500 mL, 2 m³.
• Materials are kinds of matter used to make objects.
• We classify non-living things by properties, just like we classify living things.
Daily-Life Sorting Ideas
Kitchen
Store by type/use (cereals, pulses, spices, oils) or by containers (transparent jars help you see contents).
Shop/Wardrobe
Group by material, fragility, use frequency.
Waste bins
Pick container materials considering leak-proof, safe for glass, dry vs wet.
Mini-Labs / Activities (class-ready)
- 1Shine Hunt: Collect foil, copper wire, chalk, wood—rank lustre; note if shine is real metal or polish/coating.
- 2Scratch Scale: Use the same key to scratch chalk/wood/aluminium/iron—order from soft → hard.
- 3Window Test: Label classroom items T/Tr/O (transparent/translucent/opaque).
- 4Mix & Note: Stir salt, sugar, sand, sawdust, chalk in water—record soluble/insoluble; try oil on top.
- 5Balance Compare: Half-filled cups of water, sand, pebbles—weigh & order by mass.
- 6Volume Sense: Pour water from two bottles into identical tumblers; compare levels → volume.
Fun Facts / Culture Corner
- Ancient pottery (Harappan): refined clays, slips, painted designs; baked terracotta jars for storage.
- Ayurveda's 20 properties (guṇa) show an early system of classifying matter (e.g., heavy–light, hot–cold, smooth–rough).
HOTS / Exam-Style Questions
- 1
Chair challenge: From wood/iron/plastic/bamboo/cement/stone—pick the best for (i) hardness (long-term use), (ii) light weight, (iii) not cold in winter, (iv) easy cleaning—justify.
- 2
Transparent containers are common in shops—explain why.
- 3
Mystery pair: X dissolves and is hard; Y doesn't dissolve and is soft—name examples & explain.
- 4
Sort horse, oil, air, frosted glass, copper, butter paper, chalk into material type and see-through class.
- 5
Your friend calls air "not matter" since we can't see it. Refute using mass/volume ideas.
Suggested Visuals to Add
- Property Wall: Lustre vs Non-lustre; Hard vs Soft (photo tiles).
- See-through Strip: Transparent ↔ Translucent ↔ Opaque with real samples.
- Mixing Map: Soluble/insoluble table + oil-water layer sketch.
- Units Poster: g–kg, mL–L–m³ with correct symbol rules & examples.
- Object → Material map: "Pen" exploded view (plastic/metal/ink).
Quick Recap
- Objects come from many materials; we choose by properties & purpose.
- Classification helps compare & decide quickly.
- Core properties: lustre, hard/soft, transparent/translucent/opaque, soluble/insoluble, mass, volume.
- Matter = mass + volume; write units properly (7 kg, 500 mL, 2 m³).