Class 6 Science Chapter 6 Notes
๐งฑ Materials Around Us
(New NCERT "Curiosity" | 2025-26)
๐ Chapter Overview
This chapter explores the materials that make up objects around us, their properties, how they are classified, and introduces the concept of matter. It covers properties like lustre, hardness, transparency, solubility, mass and volume.
๐ก Opening Sanskrit Quote from Rasaratnasamuchchaya: "The materials used to make a crucible are clay and iron." — showing that knowledge of materials existed in ancient India!
๐ Key Points
- Every object is made up of materials (paper, wood, glass, metal, plastic, clay, etc.)
- Materials are selected based on their properties and the purpose of the object
- Materials can be classified based on properties like lustre, hardness, transparency, solubility
- Matter = anything that occupies space and has mass
- The two properties shared by ALL materials = Mass and Volume
๐ 6.1 Observing Objects Around Us
- All things around us are made up of materials
- Material = Any substance that is used to create an object
- Examples: paper, wood, cloth, glass, metal, plastic, clay
- One object can be made from different materials (e.g., a pen = plastic + metal + ink)
- One material can be used to make many different objects (e.g., iron = nails, utensils, tools)
๐บ Ancient Indian Pottery: The earliest pottery in the Indian subcontinent dates back 7,000–8,000 years (Lahuradewa and Mehrgarh). The Harappan Civilisation (2600–1900 BCE) had advanced pottery with geometric patterns. Baked clay is called terracotta.
๐️ 6.2 How to Group Materials?
- Classification = The method of arranging objects into groups based on common properties
- Objects can be classified based on: shape, colour, hardness, softness, shine, material
- Key insight: An object can be made of different materials AND the same material can make different objects
- We choose a material based on its properties and the purpose of the object
- Example: A tumbler must be made from a material that can hold water
๐ฌ 6.3 Properties of Materials
6.3.1 ✨ Lustre (Appearance)
| Type | Description | Examples |
|---|---|---|
| Lustrous | Shiny surface when light falls on it | Iron, Copper, Zinc, Aluminium, Gold, Silver, Bronze, Steel |
| Non-lustrous | Dull surface, no shine | Paper, Wood, Rubber, Jute, Plastic |
⚠️ Important: Not all lustrous materials are metals! Some non-metals are made shiny by polishing or coating with plastic/wax. And metals may lose their lustre due to air and moisture — we notice lustre on freshly cut surfaces. ๐ฃ️ "All that glitters is not gold!" — old saying
6.3.2 ๐ช Hardness and Softness
| Type | Description | Examples |
|---|---|---|
| Hard | Difficult to compress or scratch | Stone, Iron, Brick, Diamond |
| Soft | Easy to compress or scratch | Sponge, Eraser, Candle, Cotton |
- Use a metal key to scratch different surfaces to test hardness
- These properties are relative: Rubber is harder than sponge but softer than iron!
| Object | Hard/Soft | Material |
|---|---|---|
| Brick | Hard | Baked clay |
| Pillow | Soft | Cotton/foam |
| Tumbler | Hard | Glass/plastic |
| Sweater | Soft | Wool/fibre |
6.3.3 ๐️ Transparency — Can We See Through?
| Type | Description | Examples |
|---|---|---|
| Transparent | Things can be seen clearly through it | Glass, Water, Air, Cellophane paper, Window glass |
| Translucent | Things can be seen but NOT clearly | Butter paper, Frosted glass, Oiled paper |
| Opaque | Things cannot be seen at all through it | Wood, Cardboard, Metals, Brick, Stone |
Story Example from Book:
- Ghulan hid behind a wall → wall = Opaque
- Sheeta hid behind a big tree → tree = Opaque
- Sara hid behind frosted glass door → door = Translucent
- Sheeta's brother could see through glass window → window glass = Transparent
Classification of objects:
| Transparent | Translucent | Opaque |
|---|---|---|
| Glass tumbler | Butter paper | Eraser |
| Window glass | Frosted glass | Wooden board |
| Water | Oiled paper | Brick, Metal |
๐ก Is water transparent? Yes! But if mud is mixed in water it becomes less transparent (turbid).
6.3.4 ๐ง Solubility — What Dissolves in Water?
| Type | Description | Examples |
|---|---|---|
| Soluble | Completely disappears (dissolves) in water | Sugar, Salt, Glucose |
| Insoluble | Does NOT disappear/mix with water | Sand, Chalk powder, Sawdust, Stone |
Activity Results:
| Material | Soluble / Insoluble |
|---|---|
| Sugar | ✅ Soluble |
| Salt | ✅ Soluble |
| Chalk powder | ❌ Insoluble |
| Sand | ❌ Insoluble |
| Sawdust | ❌ Insoluble |
Important Points about Solubility:
- Some liquids mix completely with water (vinegar) while others form a separate layer (oil)
- Oxygen gas dissolves in water → essential for aquatic life (fish, plants in water)
- Water is important for our body because it can dissolve a large number of materials
๐ฅค Make Your Own ORS! ORS (Oral Rehydration Solution) = 6 teaspoons sugar + ½ teaspoon salt in 1 litre of boiled and cooled water. Used to treat dehydration.
6.3.5 ⚖️ Mass — How Heavy or Light?
- The property of being heavier or lighter is called Mass
- Heavier object = more mass
- Lighter object = less mass
- Unit of mass: gram (g) and kilogram (kg)
- SI unit of mass = Kilogram (kg)
๐ Writing rule: "7 kg" NOT "7 kgs". Always leave space between number and unit.
6.3.6 ๐ฆ Volume — How Much Space?
- Every material/object occupies space
- The space occupied by matter is called its Volume
- Example: A half-filled glass has less volume of water than a fully-filled glass
- Units of volume: Litre (L) and Millilitre (mL)
- SI unit of volume: cubic metre (m³)
๐ Writing rules:
- Litre = capital L
- Millilitre = mL (m is lowercase, L is uppercase)
- "500 mL" NOT "500ml"
- 1 m³ = 1000 L
๐ 6.4 What is Matter?
✅ "Anything that occupies space and has mass is called MATTER."
- Mass and Volume are the two properties present in ALL materials
- Everything around us — water, sand, air, table, book, you — all are matter
- Materials = types of matter used for making objects
- Even Air is matter because it occupies space and has mass!
Units Summary:
| Property | Unit | Symbol |
|---|---|---|
| Mass | gram / kilogram | g / kg |
| Volume | litre / millilitre | L / mL |
| Volume (SI) | cubic metre | m³ |
๐ Important Definitions
| Term | Definition |
|---|---|
| Material | Any substance used to create an object |
| Classification | Method of arranging objects into groups based on common properties |
| Lustrous | Materials with shiny surface (mostly metals) |
| Non-Lustrous | Materials without shiny surface |
| Hard | Materials difficult to compress or scratch |
| Soft | Materials easy to compress or scratch |
| Transparent | Materials through which things can be seen clearly |
| Translucent | Materials through which things can be seen but not clearly |
| Opaque | Materials through which things cannot be seen at all |
| Soluble | Materials that dissolve completely in water |
| Insoluble | Materials that do not dissolve in water |
| Mass | The quantity of matter in an object (measured in kg/g) |
| Volume | The space occupied by matter (measured in L/mL) |
| Matter | Anything that occupies space and has mass |
❓ NCERT Exercise Questions & Answers
Q2. Unscramble and match:
| Scrambled | Word | Match |
|---|---|---|
| T R E M A T | Matter | (b) Occupies space and has mass |
| U L S B E L O | Soluble | (d) Mixes completely in water |
| T N E R P A S N A R T | Transparent | (a) Objects can be seen clearly through it |
| E R U S T L | Lustre | (c) Shiny surface |
Q3. Why are storage containers usually transparent?
Answer: Transparent containers allow us to see the contents inside without opening them. This makes it easy to identify what is stored, check quantity, and find items quickly without having to open each container.
Q4. True [T] or False [F]:
(i) Wood is translucent while glass is opaque. → F Correction: Wood is opaque while glass is transparent.
(ii) Aluminium foil has lustre while an eraser does not. → T
(iii) Sugar dissolves in water whereas sawdust does not. → T
(iv) An apple is matter because it occupies no space and has mass. → F Correction: An apple IS matter but because it DOES occupy space AND has mass.
Q5. Which chair material fulfils these properties?
(i) Hardness (does not bend) → Stone, Iron, Wood (ii) Lightweight (easy to carry) → Plastic, Bamboo (iii) Does not feel cold in winters → Wood, Plastic, Bamboo (iv) Can be cleaned regularly → Plastic, Iron
Q6. Containers for waste collection:
(i) Food waste → Plastic container (light, can be cleaned, does not rust) (ii) Broken glass → Metal/thick plastic container (hard, not punctured by glass) (iii) Wastepaper → Any lightweight container — even cardboard (since it's dry)
Properties to consider: hardness, waterproofing, ease of cleaning, strength
Q7. Fill in the blanks: Air is transparent and the wooden door is opaque. Answer: (i) transparent, opaque ✅
Q8. Mystery materials X and Y:
- Material X → rigid (hard), dissolves in water → Salt (hard crystal, soluble)
- Material Y → changes shape easily (soft), does not dissolve in water → Chalk/Clay (soft, insoluble) or Wax
Q9. Who am I? (a) I have lustre → Metal (e.g., iron, copper) (b) I can be easily compressed → Sponge/Rubber (c) I am hard and soluble in water → Salt/Sugar (d) You cannot see clearly through me → Translucent material (frosted glass/butter paper) (e) I have mass and volume but you cannot see me → Air
✅ MCQ Questions
1. Which of the following is a lustrous material? a) Wood b) Rubber c) Copper d) Paper ✅ Answer: c) Copper
2. Frosted glass is an example of: a) Transparent b) Opaque c) Translucent d) Lustrous ✅ Answer: c) Translucent
3. Which material is soluble in water? a) Sand b) Chalk c) Sawdust d) Salt ✅ Answer: d) Salt
4. Matter is defined as anything that: a) Has colour b) Occupies space and has mass c) Is hard d) Is visible ✅ Answer: b)
5. SI unit of mass is: a) Gram b) Litre c) Kilogram d) Metre ✅ Answer: c) Kilogram
6. Which property is shared by ALL materials? a) Lustre b) Hardness c) Mass and Volume d) Transparency ✅ Answer: c) Mass and Volume
7. Which is an example of opaque material? a) Glass b) Water c) Cellophane d) Wood ✅ Answer: d) Wood
8. Oxygen dissolving in water is important because: a) It makes water heavy b) It helps aquatic animals and plants survive c) It makes water transparent d) It makes water taste better ✅ Answer: b)
๐ง Quick Revision Table
| Property | Examples |
|---|---|
| Lustrous | Iron, Copper, Gold, Aluminium |
| Non-Lustrous | Paper, Wood, Rubber, Jute |
| Hard | Stone, Brick, Iron, Diamond |
| Soft | Sponge, Cotton, Wax, Eraser |
| Transparent | Glass, Water, Air, Cellophane |
| Translucent | Butter paper, Frosted glass |
| Opaque | Wood, Metal, Cardboard, Brick |
| Soluble | Sugar, Salt, Glucose |
| Insoluble | Sand, Chalk, Sawdust |
๐ Ancient Indian Connection!
Ayurveda (Indian medical system) described 20 properties (called guแนa) as 10 pairs of opposites to classify ALL physical matter — heavy/light, cold/hot, hard/soft, solid/liquid, etc. This is one of the world's earliest classification systems for matter! ๐ฎ๐ณ
๐ Exam Tips:
- The most asked questions are about transparent/translucent/opaque with examples — learn the definitions clearly!
- Know the definition of matter by heart — "anything that occupies space and has mass"
- Remember: mass = kg, volume = L/mL, both are properties of ALL matter
- The lustre topic often appears with the question — "Are all lustrous materials metals?" (Answer: No!) ๐ฏ