Chapter 4: Materials of Daily Use 🏺
A Comprehensive Guide for PSTET Paper-2 (Science)
Chapter 4: Materials of Daily Use 🏺
A Comprehensive Guide for PSTET Paper-2 (Science)
Chapter Overview
| Section | Topic | PSTET Weightage | Page No. |
|:---:|:---|::---:|:---:|
| 4.1 | Classification of Materials | High | 2 |
| 4.2 | Objects and the Materials They Are Made Of | Medium | 7 |
| 4.3 | Properties of Materials | High | 10 |
| 4.4 | Change of State of Matter | High | 15 |
| 4.5 | Water as a Universal Solvent | Medium | 20 |
| Practice Zone | MCQs & Pedagogical Questions | - | 24 |
Learning Objectives 🎯
After studying this chapter, you will be able to:
✅ Classify materials based on various properties like hardness, solubility, transparency, and buoyancy
✅ Distinguish between objects and the materials they are made from
✅ Explain the physical properties of materials and their importance in selecting materials for specific purposes
✅ Describe the six changes of state: melting, boiling, evaporation, condensation, freezing, and sublimation
✅ Explain why water is called the "universal solvent" using its molecular structure
✅ Apply pedagogical strategies to teach materials and their properties effectively to upper primary students
Pedagogical Link 🔗
For Teachers: This chapter directly aligns with:
Class 6 Science NCERT Chapter 4: "Sorting Materials into Groups"
Class 6 Science NCERT Chapter 5: "Separation of Substances"
Class 9 Science NCERT Chapter 1: "Matter in Our Surroundings"
Teaching Tips:
Create a "Material Museum" in your classroom with samples of different materials for students to touch and explore
Use the "Object Hunt" activity where students identify materials around them
Conduct simple kitchen experiments to demonstrate solubility and changes of state
Encourage students to think about "Why this material?" when observing everyday objects
Section 4.1: Classification of Materials 🏷️
Introduction
Look around you—everything you see is made of some material. Your desk is made of wood, your water bottle is made of plastic, and your window is made of glass. But have you ever wondered why different objects are made from different materials? The answer lies in the properties of these materials .
Materials are classified based on their properties to make it easier to study them and choose the right material for a specific purpose .
4.1.1 Quick Reference: Classification of Materials at a Glance
Table 4.1: Summary of Material Classifications
4.1.2 Detailed Classification with Activities
A. Classification Based on Appearance ✨
Materials can be classified as lustrous (shiny) or non-lustrous (dull) based on how they look .
| Category | Definition | Examples | PSTET Point |
|---|---|---|---|
| Lustrous Materials | Materials with a shiny appearance | Gold, Silver, Copper, Aluminium, Steel | Metals generally have lustre |
| Non-lustrous Materials | Materials with a dull appearance | Wood, Chalk, Paper, Plastic, Rubber | Non-metals are usually dull |
📝 Important Note: Some metals lose their lustre when exposed to air and moisture. For example:
Iron reacts with oxygen and moisture to form rust (reddish-brown layer)
Silver reacts with hydrogen sulphide in air to form a black layer (tarnishing)
Gold does not lose its lustre—that's why it's used for jewellery
B. Classification Based on Texture 🖐️
Texture refers to how a material feels when touched .
| Category | Description | Examples |
|---|---|---|
| Smooth Materials | No bumps or ridges on surface | Glass sheet, Flower petals, Apple surface, Polished metal |
| Rough Materials | Have bumps or ridges that can be felt | Rocks, Sandpaper, Tree bark, Unpolished stone |
🧪 Classroom Activity: Create a "Feely Bag" with different objects. Ask students to put their hand in, feel the object, and describe whether it's smooth or rough before seeing it.
C. Classification Based on Hardness 💪
Hardness refers to how difficult it is to compress or scratch a material .
| Category | Definition | Examples | Property |
|---|---|---|---|
| Hard Materials | Difficult to compress, cut, bend, or scratch | Iron, Diamond, Steel, Stone, Glass | Maintain shape under pressure |
| Soft Materials | Easy to compress, cut, or scratch | Cotton, Sponge, Chalk, Wax, Rubber | Change shape easily |
📌 Fascinating Fact: Diamond is the hardest natural material on Earth. It can cut glass and even scratch other hard materials like tungsten !
📝 PSTET Note: Some metals like gold and sodium are actually soft metals that can be cut easily, while non-metals like diamond are extremely hard .
D. Classification Based on Solubility 💧
Solubility refers to whether a material dissolves in water .
Table 4.2: Solubility Classification
For Liquids in Water:
| Category | Definition | Examples |
|---|---|---|
| Miscible Liquids | Mix completely with water | Ink, Vinegar, Lemon juice, Alcohol |
| Immiscible Liquids | Form separate layer on water | Edible oil, Kerosene, Petrol |
For Gases in Water:
🧪 Activity 4.1: Testing Solubility
| Step | Action | Observation |
|---|---|---|
| 1 | Take 5 test tubes half-filled with water | - |
| 2 | Add small amounts of salt, sugar, sand, sawdust, and glucose to each | - |
| 3 | Stir well and wait for a few minutes | - |
| 4 | Observe what happens | Salt, sugar, glucose dissolve; sand and sawdust remain |
E. Classification Based on Transparency 👁️
Transparency is the property that determines how much light passes through a material .
Table 4.3: Types of Transparency
Human organs are opaque to normal light but transparent to X-rays
Bones are opaque to X-rays because calcium blocks them completely
When oil is dropped on paper, the paper becomes translucent at that spot
Your palm is actually translucent—hold it against a flashlight and see!
F. Classification Based on Buoyancy 🚤
Buoyancy refers to whether a material floats or sinks in water .
📌 Important Concept: Density
Density = Mass per unit volume
Materials with density less than water (1 g/cm³) float
🧠 Think About This: Why does a huge ship made of iron float while a small iron nail sinks?
Answer: The ship's shape displaces more water, creating greater buoyant force that supports its weight. This is Archimedes' principle!
G. Classification Based on Magnetic Property 🧲
| Category | Definition | Examples |
|---|---|---|
| Magnetic Materials | Attracted to a magnet | Iron, Nickel, Cobalt, Steel |
| Non-magnetic Materials | Not attracted to a magnet | Wood, Plastic, Glass, Cotton, Paper, Aluminium, Copper |
📝 PSTET Note: Aluminium and copper are metals but are NOT magnetic!
H. Classification Based on Conductivity ⚡
| Category | Definition | Examples |
|---|---|---|
| Conductors | Allow heat/electricity to pass through | Copper, Aluminium, Silver, Iron (metals) |
| Insulators | Do not allow heat/electricity to pass | Wood, Plastic, Rubber, Glass, Cotton |
I. Other Important Properties
4.1.3 Pedagogical Implications
Section 4.2: Objects and the Materials They Are Made Of 🔍
Introduction
It's important to distinguish between an object and the material it is made from. An object is something you can touch, while a material is what the object is made from .
4.2.1 Object vs. Material: The Key Difference
| Term | Definition | Example |
|---|---|---|
| Object | Something you can touch and use | A chair, a bottle, a book |
| Material | The substance an object is made from | Wood, plastic, paper |
One material can make many objects - Wood can make chairs, tables, doors, pencils
One object can be made of multiple materials - A bicycle has metal frame, rubber tyres, plastic handles
Same object can be made from different materials - Bowls can be made of plastic, metal, wood, or glass
4.2.2 Common Materials and Their Objects
Table 4.4: Materials and the Objects They Make
4.2.3 Fascinating Facts About Materials
| Fact | Details |
|---|---|
| Aluminium cans | Most recycled item in the world |
| Medieval castles | Made from stone—plentiful and strong for defence |
| Wool | Comes from sheep; warm, hard-wearing, and absorbent |
| Tin foil | Invented in USA during WWII to store food; now made from aluminium |
| Mercury | Metal that is liquid at room temperature |
| Eiffel Tower | Made of wrought iron; weighs 7,300 tonnes (equal to 5000 cars!) |
| Seawater | Contains tiny traces of gold |
4.2.4 Why Choose a Particular Material?
When choosing a material for making an object, we consider two factors :
The property of the material
The purpose/use of the object
Table 4.5: Why Specific Materials Are Chosen
4.2.5 Pedagogical Implications
Section 4.3: Properties of Materials 📋
Introduction
Properties are characteristics that describe a material or substance—such as colour, shape, hardness, and behaviour with other substances . Understanding properties helps us choose the right material for the right purpose.
4.3.1 Comprehensive Table of Material Properties
Table 4.6: Properties of Materials - Complete Reference
4.3.2 Detailed Explanation of Key Properties
A. Appearance
B. Hardness
C. Solubility
Insoluble materials remain visible, either settling or floating
Gases like oxygen and CO₂ dissolve in water—essential for aquatic life
D. Transparency
| Type | Light Transmission | Visibility | Examples |
|---|---|---|---|
| Transparent | All light passes | Clearly through | Air, pure water, clear glass |
| Translucent | Some light passes | Not clearly through | Frosted glass, tracing paper, oily paper |
| Opaque | No light passes | Cannot see through | Wood, metal, stone, cardboard |
E. Buoyancy and Density
Archimedes' principle: Buoyant force equals weight of displaced fluid
Ships float because their shape displaces large volume of water
4.3.3 Pedagogical Implications
| Teaching Strategy | Description | PSTET Focus |
|---|---|---|
| Property Stations | Set up stations for testing different properties | Hands-on learning |
| Prediction Activities | Predict properties before testing | Scientific method |
| Recording Observations | Maintain property tables in notebooks | Documentation skills |
| Real-world Connections | Link properties to everyday uses | Practical application |
Section 4.4: Change of State of Matter 🔄
Introduction
Matter exists in three main states—solid, liquid, and gas. Under different conditions of temperature and pressure, matter can change from one state to another. These are called changes of state .
4.4.1 The Six Changes of State
Table 4.7: Changes of State - Complete Reference
| Change | From State | To State | Energy Change | Example |
|---|---|---|---|---|
| Melting | Solid | Liquid | Gains heat (energy absorbed) | Ice melts to water |
| Freezing | Liquid | Solid | Loses heat (energy released) | Water freezes to ice |
| Boiling/Evaporation | Liquid | Gas | Gains heat (energy absorbed) | Water boils to steam |
| Condensation | Gas | Liquid | Loses heat (energy released) | Steam condenses on cold surface |
| Sublimation | Solid | Gas | Gains heat (energy absorbed) | Camphor, naphthalene balls disappear |
| Deposition | Gas | Solid | Loses heat (energy released) | Frost formation, snow in clouds |
4.4.2 Particle Explanation of States of Matter
Table 4.8: Particle Arrangement in Different States
| State | Particle Arrangement | Particle Movement | Shape | Volume |
|---|---|---|---|---|
| Solid | Very close together in regular pattern | Vibrate about fixed positions | Fixed | Fixed |
| Liquid | Close together but no regular pattern | Slide past each other | Not fixed (takes shape of container) | Fixed |
| Gas | Widely separated (10x further apart) | Move randomly at high speed | Not fixed | Not fixed |
4.4.3 Detailed Explanation of Each Change
A. Melting (Solid → Liquid) 🧊➡️💧
Definition: Process where a solid turns into a liquid when heated
Temperature point: Melting point (specific for each substance)
Examples:
Ice melts to water at 0°C
Wax melts when candle burns
Butter melts in a hot pan
Particle explanation: Particles gain heat energy, vibrate more, overcome forces holding them in fixed positions
B. Freezing (Liquid → Solid) 💧➡️🧊
Definition: Process where a liquid turns into a solid when cooled
Temperature point: Freezing point (same as melting point)
Examples:
Water freezes to ice at 0°C
Molten wax solidifies
Making ice lollies
Particle explanation: Particles lose heat energy, move slower, become fixed in positions
C. Boiling (Liquid → Gas - throughout) 💧➡️💨
Definition: Rapid vaporization throughout the liquid at boiling point
Temperature point: Boiling point (100°C for water)
Characteristics: Bubbles form throughout the liquid
Examples: Boiling water for cooking, boiling milk
D. Evaporation (Liquid → Gas - at surface) 💧➡️💨
Definition: Slow vaporization from liquid surface at any temperature
Temperature: Occurs at all temperatures (faster when hot)
Characteristics: Only at surface; no bubbles
Examples: Drying of clothes, puddles disappearing, sweating
Factors affecting evaporation:
Temperature (higher = faster)
Surface area (larger = faster)
Humidity (lower = faster)
Wind speed (higher = faster)
E. Condensation (Gas → Liquid) 💨➡️💧
Definition: Process where gas turns into liquid when cooled
Examples:
Water droplets on cold glass
Fog on mirror after hot shower
Clouds forming in sky
Morning dew on grass
Particle explanation: Gas particles lose energy, come closer together to form liquid
F. Sublimation (Solid → Gas directly) 🧊➡️💨
Definition: Process where solid turns directly into gas without passing through liquid state
Examples:
Camphor (kapur) disappearing
Naphthalene balls (moth balls) shrinking
Dry ice (solid CO₂) turning to gas
Ammonium chloride
Particle explanation: Particles gain enough energy to break free directly from solid to gas
G. Deposition (Gas → Solid directly) 💨➡️🧊
Definition: Process where gas turns directly into solid without passing through liquid state
Examples:
Frost formation on cold surfaces
Snow formation in clouds
Sublimate of iodine on cool surface
4.4.4 Important Points for PSTET
| Point | Explanation |
|---|---|
| Mass remains constant | Number of particles doesn't change during change of state |
| Substance remains same | Water molecules are still H₂O whether ice, water, or steam |
| Physical change | Changes of state are reversible physical changes, not chemical changes |
| Energy involved | Melting, boiling, evaporation, sublimation need heat; freezing, condensation release heat |
4.4.5 Water Cycle - Application of Changes of State 🌍
| Process | Change of State | Role in Water Cycle |
|---|---|---|
| Evaporation | Liquid → Gas | Water from oceans, lakes turns to vapour |
| Condensation | Gas → Liquid | Water vapour forms clouds |
| Precipitation | Liquid/Solid → Falls | Rain (liquid) or snow (solid) falls to Earth |
| Melting | Solid → Liquid | Snow and ice melt to water |
| Freezing | Liquid → Solid | Water freezes in cold regions |
4.4.6 Pedagogical Implications
| Teaching Strategy | Description | PSTET Focus |
|---|---|---|
| Demonstration | Show melting ice, boiling water, condensation on mirror | Visual learning |
| Particle Model | Use balls or students to model particle arrangement | Concrete understanding |
| Water Cycle Project | Students draw and explain water cycle | Integration with EVS |
| Kitchen Experiments | Observe changes while cooking | Real-life connections |
Section 4.5: Water as a Universal Solvent 💧
Introduction
Water is often called the "universal solvent" because it dissolves more substances than any other liquid . This remarkable property makes water essential for life, as countless chemical reactions occur in aqueous solutions within living organisms .
4.5.1 Why Is Water Such a Good Solvent?
The secret lies in water's polarity and its ability to form hydrogen bonds .
Table 4.9: Water's Molecular Structure and Properties
In a water molecule:
Oxygen is more electronegative, pulling electrons towards itself
This creates a partial negative charge (δ-) on the oxygen atom
Hydrogen atoms have a partial positive charge (δ+)
This charge separation makes water polar
4.5.2 How Water Dissolves Substances
A. Dissolving Ionic Compounds (e.g., Salt) 🧂
When salt (NaCl) is added to water:
| Step | Process |
|---|---|
| 1 | Water molecules surround the salt crystal |
| 2 | Negative ends of water (oxygen) attract positive sodium ions (Na⁺) |
| 3 | Positive ends of water (hydrogen) attract negative chloride ions (Cl⁻) |
| 4 | Attractions overcome ionic bonds holding NaCl together |
| 5 | Individual ions become surrounded by water molecules (hydration shell) and disperse |
Result: Salt dissolves completely in water
B. Dissolving Polar Molecules (e.g., Sugar) 🍬
Sugar molecules are polar but not ionic. Water forms hydrogen bonds with the -OH groups of sugar, pulling sugar molecules apart and into solution.
C. Why Oil Does NOT Dissolve in Water 🛢️
4.5.3 Hydrophilic vs. Hydrophobic Substances
4.5.4 Is Water Really a "Universal" Solvent?
The Truth: While water is excellent at dissolving many substances, it's not truly universal .
| Dissolves Well | Does NOT Dissolve Well |
|---|---|
| Ionic compounds (salts) | Non-polar substances (oils, fats) |
| Polar molecules (sugar, alcohol) | Hydrocarbons (petrol, kerosene) |
| Acids and bases | Waxes |
| Many gases (O₂, CO₂) | Some plastics |
📝 PSTET Note: Water is called "universal solvent" because it dissolves more substances than any other common liquid, not because it dissolves everything .
4.5.5 Importance of Water as a Solvent in Nature and Life
A. In Living Organisms
| Role | Explanation |
|---|---|
| Blood plasma | Water dissolves and transports nutrients, hormones, and waste |
| Cytoplasm | Cellular reactions occur in aqueous medium |
| Digestion | Water helps dissolve nutrients for absorption |
| Excretion | Waste products dissolved in urine |
B. In Environment
| Role | Explanation |
|---|---|
| Water cycle | Water evaporates, condenses, precipitates, distributing dissolved minerals |
| Soil nutrients | Plants absorb dissolved minerals through water |
| Aquatic life | Oxygen dissolved in water supports fish and other organisms |
C. In Daily Life
| Application | Explanation |
|---|---|
| Cooking | Dissolving salt, sugar, spices in water |
| Cleaning | Soap dissolves in water to remove dirt |
| Medicines | Many drugs are water-soluble |
| Beverages | Tea, coffee, juices are aqueous solutions |
4.5.6 Pedagogical Implications
| Teaching Strategy | Description | PSTET Focus |
|---|---|---|
| Demonstration | Show salt dissolving in water vs. oil in water | Visual understanding |
| Model Making | Use ball-and-stick models to show water's polarity | Concrete representation |
| Concept Mapping | Link water's structure to its solvent properties | Connects concepts |
| Real-life Examples | Discuss why soap is needed to remove oil | Practical application |
Chapter Summary: Key Points for Revision 📝
Quick Revision Table
Practice Zone: PSTET-Style Questions 🎯
Content-Based MCQs
Q1. Which of the following is a lustrous material?
a) Wood
b) Chalk
c) Gold
d) Paper
Q2. A material through which you cannot see at all is called:
a) Transparent
b) Translucent
c) Opaque
d) Luminous
Q3. Which of the following will dissolve in water?
a) Sand
b) Sawdust
c) Sugar
d) Coconut oil
Q4. The process of changing from solid to gas directly is called:
a) Evaporation
b) Condensation
c) Sublimation
d) Melting
Q5. Water is called a universal solvent because:
a) It dissolves all substances
b) It is polar and dissolves many substances
c) It is available everywhere
d) It has high boiling point
Q6. Which of the following materials will FLOAT on water?
a) Stone
b) Iron nail
c) Cork
d) Glass marble
Q7. An object that is made from multiple materials is:
a) Wooden chair
b) Glass bottle
c) Bicycle
d) Plastic bucket
Q8. The process of water turning into water vapour on heating is called:
a) Condensation
b) Evaporation
c) Freezing
d) Melting
Q9. Which of the following is NOT a magnetic material?
a) Iron
b) Nickel
c) Cobalt
d) Copper
Q10. Frost formed on leaves in winter is an example of:
a) Condensation
b) Evaporation
c) Deposition
d) Sublimation
Pedagogical MCQs
Q11. A teacher brings different objects to class and asks students to identify what materials they are made from. This activity promotes:
a) Rote learning
b) Observation and classification skills
c) Memorization
d) Textbook dependency
Q12. To teach the concept of solubility effectively, the best approach would be:
a) Give definition and ask students to memorize
b) Demonstrate with salt, sugar, sand in water, letting students observe
c) Show a video only
d) Draw diagrams on board
Q13. While teaching changes of state, a teacher should emphasize:
a) Memorizing all six names
b) Understanding the particle model and energy changes
c) Writing long definitions
d) Copying from textbook
Q14. A student asks, "Why does an iron ship float but an iron nail sinks?" The teacher should explain using:
a) "It's magic"
b) Archimedes' principle and displacement of water
c) "Ships are special"
d) Ignore the question
Q15. The most effective way to teach "objects and materials" to Class 6 students is:
a) Lecture method
b) Object hunt around classroom/school
c) Reading textbook silently
d) Writing definitions repeatedly
Answer Key with Explanations
Pedagogical Reflection for Teachers 🤔
Think-Pair-Share Activity:
Think: How would you set up a "Material Discovery Corner" in your classroom with 10 different materials for students to explore?
Pair: Discuss with a colleague how you would explain the difference between evaporation and boiling to students using everyday examples.
Share: Design a 15-minute activity to teach why different materials are chosen for different objects (e.g., why windows use glass, not wood).
NCERT Textbook Linkages 📚
| Class | Chapter | Topic |
|---|---|---|
| Class 6 | Chapter 4 | Sorting Materials into Groups |
| Class 6 | Chapter 5 | Separation of Substances |
| Class 9 | Chapter 1 | Matter in Our Surroundings |
| Class 11 | Chapter 5 | States of Matter |
Chapter End Notes
Key Terminology Glossary
Quick Tips for PSTET Aspirants ⚡
✅ Memorize with Mnemonics:
Changes of State: "My Friend Bobby Eats Cold Soup Daily"
Melting, Freezing, Boiling, Evaporation, Condensation, Sublimation, Deposition
Transparency Types: "Tea Tastes Okay" = Transparent, Translucent, Opaque
Hydrophilic vs Hydrophobic: "Like Likes Like" - Polar likes polar (hydrophilic), non-polar likes non-polar (hydrophobic)
✅ Common Exam Traps:
Gold vs Silver: Both are lustrous, but gold doesn't tarnish, silver does
Aluminium vs Iron: Both metals, but aluminium is non-magnetic, iron is magnetic
Evaporation vs Boiling: Evaporation at surface at any temperature; boiling throughout at boiling point
Sublimation vs Evaporation: Sublimation is solid→gas; evaporation is liquid→gas
Universal Solvent: Water dissolves many substances, but NOT everything (oils don't dissolve)
✅ Important Facts:
✅ Application-Based Questions:
"Why are cooking utensils made of metal but handles made of plastic?"
"Why do we see water droplets on the outside of a cold drink bottle?"
"Why does sugar dissolve faster in hot tea than in cold water?"
Answer: Solubility and rate of dissolution increase with temperature
Answers to "Check Your Understanding"
[To be filled by student]
📝 Note for Self-Study: After completing this chapter, ensure you can:
Classify 10 materials based on 5 different properties
Explain the difference between an object and a material with 5 examples
Explain why water is a good solvent using its molecular structure
Give 5 examples each of hydrophilic and hydrophobic substances
Answer "Why this material?" questions for 10 common objects
Design a simple experiment to demonstrate evaporation and condensation
End of Chapter 4
Next Chapter: Chapter 5 - Organisms and Their Habitat
Topics Covered: Living and Non-living, Habitat and Adaptation, Different Ecosystems
