Sorting Materials into Groups

Sorting Materials into Groups - Class 6 Science Chapter Notes with Experiments, Examples & Solutions

Introduction to Sorting Materials into Groups

What is Sorting Materials into Groups?

Sorting materials into groups is the process of organizing objects based on their similar characteristics or properties. This classification helps us understand materials better, locate them easily, and use them effectively for specific purposes.

Why Do We Sort Materials?

The classification of materials offers two main advantages:

1. Easy Location and Work: When materials are grouped, they're easier to find and use
2. Better Understanding: Knowing properties of one group member helps predict properties of others in that group

Real-Life Example

Visit any grocery store soaps are kept together, biscuits in another section, and vegetables separately. This sorting makes shopping easier and more efficient.

2. Classification of Objects

2.1 Living and Non-Living Objects

Objects around us can be first divided into two broad categories:

Living Objects

• Need food, water, and air for survival
• Examples: Dog, Rose, Algae, Hydrilla, Grasshopper, Cactus, Earthworm, Tree, Fish, Hen

Non-Living Objects

• Do not require food, water, or air
• Examples: Table, Toy, Clothes, Pencil, Knife, Shoes, Blackboard, Wool, Feather, Nail

2.2 Plants and Animals (Living Objects Sub-Classification)

Living objects can be further classified:

Plants

• Can make their own food using carbon dioxide, water, and sunlight
• Examples: Rose, Algae, Hydrilla, Cactus, Tree

Animals

• Cannot make their own food
• Examples: Dog, Grasshopper, Earthworm, Fish, Hen

2.3 Classification of Non-Living Objects

Non-living objects are classified based on:

• Material they're made of
• Their uses
• Color, shape, size
• Appearance, hardness, texture

Example Classification by Material:

Wood Objects	Metal Objects	Glass Objects	Plastic Objects
Table	Nail	Beaker	Toy
Chair	Utensils	Test-tube	Ruler
Bed	Magnet	Funnel	Mug
Door	Coin	Mirror	Polythene bag

3. Materials and Their Types

What is Material?

Material is the matter from which an object is made. Anything that has mass and occupies space is called matter.

Types of Materials

3.1 Natural Materials

Materials that occur naturally in nature:

• Wood
• Coal
• Rocks
• Minerals
• Water
• Gold
• Petroleum
• Cotton
• Wool
• Silk
• Leather
• Sand
• Soil

3.2 Man-Made Materials

Materials created by humans through processing:

• Iron
• Stainless steel
• Cement
• Glass
• Plastics
• Paper
• Paints
• Nylon
• Polyester
• Sugar
• Brass

Important Concepts About Materials

Concept 1: The same object can be made from different materials

• Example: A tumbler can be made of plastic, glass, stainless steel, brass, or silver

Concept 2: The same material can make many different objects

• Example: Plastic can make rulers, tumblers, mugs, buckets, pipes, lunch boxes, toys, and toothbrushes

Concept 3: Many objects are made from a combination of materials

• Example: Tea is made from water, tea leaves, sugar, and milk

4. Properties of Materials

Materials are chosen for specific purposes based on their properties. Understanding these properties helps in material selection.

4.1 Appearance (Lustre)

Materials with Lustre (Shiny Appearance)

• Have a shiny, reflective surface
• Examples: Gold, Silver, Copper, Aluminium, Iron, Steel, Stainless steel, Brass, Diamond
• Note: Some metals like iron and copper may lose shine due to air and moisture; check freshly cut surfaces

Materials without Lustre (Dull Appearance)

• Have a non-shiny, matte surface
• Examples: Paper, Cardboard, Wood, Chalk, Cotton, Plastic, Rubber, Sand

4.2 Hardness and Softness

Hard Materials

Materials that cannot be easily compressed, cut, bent, or scratched

• Examples: Iron, Steel, Wood, Stone, Brick, Glass, Bones, Teeth, Diamond
• Hardest natural material: Diamond

Soft Materials

Materials that can be easily compressed, cut, bent, molded, or scratched

• Examples: Sponge, Cotton, Wool, Foam rubber, Candle wax, Butter, Chalk, Clay, Flour, Feathers, Skin, Tomato

4.3 Solubility in Water

Soluble Materials

Materials that dissolve completely in water

• Examples: Salt, Sugar, Glucose, Citric acid, Copper sulphate
• Soluble Gases: Oxygen (important for aquatic life), Carbon dioxide (important for aquatic plants)

Insoluble Materials

Materials that do not dissolve in water

• Examples: Sand, Chalk powder, Sawdust, Oil, Stones
• Insoluble Gases: Nitrogen, Methane (marsh gas)

4.4 Density (Heaviness or Lightness with Respect to Water)

Materials Heavier than Water (Sink in water)

• Higher density than water
• Examples: Iron, Steel, Stone, Glass, Copper, Aluminium

Materials Lighter than Water (Float on water)

• Lower density than water
• Examples: Wood, Cork, Plastic bottles (empty), Oil, Wax, Ice

4.5 Transparency, Translucency, and Opaqueness

Transparent Materials

Materials through which we can see clearly; allow almost all light to pass through

• Examples: Clear glass, Clean water, Air, Alcohol, Groundnut oil
• Hindi term: Paradarshi
• Applications: Window panes, spectacles, test tubes, beakers

Translucent Materials

Materials through which we cannot see clearly; allow only some light to pass through

• Examples: Ground glass, Butter paper (tracing paper), Oiled paper, Tissue paper, Muddy water, Clouds
• Hindi term: Ardhapardarshi
• Applications: Bathroom windows (for privacy with light)

Opaque Materials

Materials through which we cannot see at all; do not allow any light to pass through

• Examples: Cardboard, Wood, Metals, Brick, Stone, Books
• Hindi term: Apardarshi
• Applications: Walls, doors, containers for privacy

5. Simple Home Experiments

Experiment 1: Testing Solubility

Materials Needed: Salt, sugar, sand, chalk powder, oil, 5 glasses of water, spoons

Procedure:

1. Take 5 glasses filled with equal amounts of water
2. Add one teaspoon of salt in glass 1
3. Add one teaspoon of sugar in glass 2
4. Add one teaspoon of sand in glass 3
5. Add one teaspoon of chalk powder in glass 4
6. Add one teaspoon of oil in glass 5
7. Stir each glass and observe after 5 minutes

Observations:

• Soluble: Salt and sugar will dissolve completely
• Insoluble: Sand, chalk powder, and oil will not dissolve

Conclusion: Water dissolves some materials (soluble) but not others (insoluble)

Experiment 2: Testing Conductivity at Home

Materials Needed: Battery (9V or AA batteries), small bulb with holder, connecting wires, test materials (spoon, plastic ruler, wooden stick, iron nail, paper clip, rubber band)

Procedure:

1. Connect the battery to the bulb holder using wires, leaving a gap in the circuit
2. Place different materials in the gap one by one
3. Observe if the bulb lights up

Observations:

• Bulb lights up (Conductors): Metal spoon, iron nail, paper clip
• Bulb doesn't light up (Insulators): Plastic ruler, wooden stick, rubber band

Conclusion: Metals conduct electricity while most non-metals don't

Safety Note: Use only low-voltage batteries for this experiment

Experiment 3: Float and Sink Test

Materials Needed: Large bowl of water, test materials (cork, stone, wooden block, iron nail, plastic bottle cap, metal coin, wax piece, paper)

Procedure:

1. Fill a large transparent bowl with water
2. Gently place each material on the water surface
3. Observe and record which materials float and which sink

Results:

• Float (Lighter than water): Cork, wooden block, plastic bottle cap, wax piece
• Sink (Heavier than water): Stone, iron nail, metal coin

Conclusion: Materials lighter than water float; materials heavier than water sink

Experiment 4: Hardness Test

Materials Needed: Sponge, iron nail, wooden stick, rubber eraser, stone, chalk piece

Procedure:

1. Try to compress each material between your fingers
2. Try to scratch each material with your fingernail
3. Record observations

Observations:

• Soft materials: Sponge, rubber eraser, chalk (can be compressed/scratched easily)
• Hard materials: Iron nail, stone, wooden stick (cannot be compressed/scratched easily)

Conclusion: Materials differ in hardness based on how easily they can be compressed, cut, or scratched

6. Activities to Teach Transparency, Opaque, and Translucent

Activity 1: Candle Visibility Test

Materials: Candle, matchbox, clear glass sheet, ground glass sheet, cardboard sheet

Steps:

1. Light a candle in a dark room
2. View the candle through clear glass - you can see the flame clearly (transparent)
3. View through ground glass you can see dim light but not the flame clearly (translucent)
4. View through cardboard you cannot see anything (opaque)

Learning Outcome: Students understand the three types of materials based on light transmission

Activity 2: Material Sorting Challenge

Materials: Collection of 20-30 everyday objects

Steps:

1. Divide students into groups
2. Give each group a mixed collection of objects
3. Ask them to sort based on:
   • First round: Living vs Non-living
   • Second round: Material type (wood, metal, plastic, glass)
   • Third round: Transparent, translucent, or opaque

Learning Outcome: Develops classification skills and reinforces multiple properties

Activity 3: Property Hunt

Materials: Worksheet with property categories

Steps:

1. Students walk around the classroom or home
2. Find and list 5 examples of:
   • Transparent materials
   • Translucent materials
   • Opaque materials
   • Hard materials
   • Soft materials
   • Materials with lustre
   • Materials without lustre

Learning Outcome: Connects theoretical knowledge with real-world observation

7. List of Everyday Examples

Metals and Non-Metals Examples

Metals in Daily Life

Metal	Common Uses	Properties
Iron	Nails, gates, tools, utensils	Hard, strong, magnetic
Copper	Electric wires, utensils, coins	Good conductor, reddish lustre
Aluminium	Cooking foils, utensils, window frames	Light, good conductor, silvery lustre
Gold	Jewelry, ornaments	Shiny, doesn't corrode, expensive
Silver	Jewelry, utensils, coins	Shiny, good conductor
Steel	Buildings, bridges, cars, utensils	Very hard, strong, durable

Non-Metals in Daily Life

Non-Metal	Common Uses	Properties
Wood	Furniture, doors, pencils	Hard, opaque, insulator
Plastic	Bottles, bags, toys, containers	Light, waterproof, insulator
Glass	Windows, bottles, mirrors	Transparent/translucent, brittle
Rubber	Tires, erasers, shoes	Soft, flexible, insulator
Paper	Books, notebooks, bags	Light, opaque, burns easily
Cotton	Clothes, bandages, wicks	Soft, absorbs water

Materials Sorted by Different Properties

By Solubility

Soluble in Water:

• Salt (in food)
• Sugar (in tea/coffee)
• Glucose (energy drink)
• Detergent powder
• Coffee powder
• Tang/Rasna powder

Insoluble in Water:

• Sand (in playgrounds)
• Oil (cooking oil)
• Chalk powder
• Sawdust
• Plastic
• Wax

By Transparency

Transparent:

• Window glass
• Water bottle
• Spectacle lenses
• Fish tank
• Clear plastic wrap
• Air

Translucent:

• Bathroom window glass
• Butter paper
• Thin cloth
• Oiled paper
• Frosted glass
• Clouds

Opaque:

• Wooden door
• Metal can
• Brick wall
• Book
• Cardboard box
• Stone

By Hardness

Hard:

• Diamond (jewelry)
• Stone (construction)
• Iron (tools)
• Glass (bottles)
• Teeth
• Bones

Soft:

• Cotton (clothes)
• Sponge (cleaning)
• Butter (food)
• Rubber foam (mattress)
• Feather (pillows)
• Clay (pottery)

8. Important Questions & Answers

Very Short Answer Questions (1 Mark)

Q1. What is classification of objects?

Answer: The sorting of objects into groups where each group has similar characteristic properties is called classification of objects.

Q2. Name the hardest natural material.

Answer: Diamond is the hardest natural material known.

Q3. What are lustrous materials?

Answer: Materials that have a shiny appearance are called lustrous materials. Example: Gold, silver, copper.

Q4. Give two examples of transparent materials.

Answer: Clear glass and clean water are transparent materials.

Q5. What is the difference between living and non-living objects?

Answer: Living objects need food, water, and air for survival, while non-living objects do not require these things.

Short Answer Questions (2-3 Marks)

Q6. Why do we classify materials into groups?

Answer: We classify materials into groups because:

• It makes it easier to locate and work with materials
• It helps in understanding materials better - knowing properties of one member helps predict properties of other members in the same group
• It organizes our knowledge systematically

Q7. Differentiate between transparent, translucent, and opaque materials with examples.

Answer:

• Transparent materials: Allow light to pass through completely; we can see clearly through them. Examples: Clear glass, water
• Translucent materials: Allow some light to pass through; we cannot see clearly through them. Examples: Ground glass, butter paper
• Opaque materials: Do not allow any light to pass through; we cannot see through them at all. Examples: Wood, metals, brick

Q8. How can you test whether a material is soluble or insoluble in water?

Answer: To test solubility:

1. Take a glass of water
2. Add a spoonful of the material to be tested
3. Stir well and wait for 5 minutes
4. Observe: If the material disappears completely, it is soluble. If particles remain visible or settle at the bottom, it is insoluble.

Q9. What is the difference between hard and soft materials? Give examples.

Answer:

• Hard materials: Cannot be easily compressed, cut, bent, or scratched. Examples: Iron, steel, stone, diamond
• Soft materials: Can be easily compressed, cut, bent, or scratched. Examples: Sponge, cotton, butter, chalk

Long Answer Questions (5 Marks)

Q10. Explain the classification of materials based on their appearance (lustre). Why do some metals lose their lustre?

Answer: Based on appearance, materials are classified into:

Materials with lustre (shiny appearance):

• All metals like gold, silver, copper, aluminium, iron have natural lustre
• Metal alloys like steel, stainless steel, brass also have lustre
• Diamond also has exceptional lustre

Materials without lustre (dull appearance):

• Non-metals like paper, cardboard, wood, chalk have dull appearance
• Plastics, rubber, sand also lack lustre

Why metals lose lustre: Some metals like iron, copper, and aluminium lose their shine when exposed to air and moisture. This happens because:

• They react with oxygen in air to form a dull layer on their surface
• Moisture accelerates this process
• To see true lustre, we should observe freshly cut metal surfaces or rub the surface with sandpaper

This is why iron objects rust and lose their shine over time.

Q11. Describe an experiment to classify materials as heavier or lighter than water.

Answer: Aim: To classify materials based on their density compared to water

Materials required: Large transparent container, water, test materials (cork, stone, wood piece, iron nail, plastic bottle cap, metal coin, wax piece)

Procedure:

1. Fill the container three-fourths with clean water
2. Gently place each test material on the water surface one by one
3. Observe whether each material floats or sinks
4. Record observations in a table

Observations:

• Materials that sink: Stone, iron nail, metal coin (heavier than water)
• Materials that float: Cork, wood piece, plastic cap, wax (lighter than water)

Conclusion:

• Materials heavier than water (higher density) sink
• Materials lighter than water (lower density) float
• This property is called density or relative heaviness

Applications: This principle explains why ships made of steel can float (hollow structure reduces overall density) and why ice floats on water.

Assertion-Reason Questions

Q12. Assertion (A): We can see clearly through a glass window.Reason (R): Glass is a transparent material that allows light to pass through it.

Answer: Both A and R are true, and R is the correct explanation of A.

Q13. Assertion (A): Cooking utensils are made of metals like copper and aluminium.Reason (R): Metals can conduct heat well.

Answer: Both A and R are true, and R is the correct explanation of A.

Q14. Assertion (A): Sugar dissolves in water but sand does not.Reason (R): All materials dissolve equally in water.

Answer: A is true but R is false. Different materials have different solubilities in water.

Multiple Choice Questions (MCQs)

Q15. Which of the following is a soft material?

(a) Iron
(b) Stone
(c) Sponge
(d) Glass
Answer: (c) Sponge

Q16. Which gas dissolved in water is essential for aquatic animals?

(a) Nitrogen
(b) Oxygen
(c) Carbon dioxide
(d) Methane
Answer: (b) Oxygen

Q17. Bathroom windows are made of ground glass because it is:

(a) Transparent
(b) Opaque
(c) Translucent
(d) Lustrous
Answer: (c) Translucent

Q18. Which of the following will float on water?

(a) Iron nail
(b) Stone
(c) Cork
(d) Metal coin
Answer: (c) Cork

Q19. Materials that have shiny appearance are said to have:

(a) Hardness
(b) Lustre
(c) Transparency
(d) Solubility
Answer: (b) Lustre

Q20. Which of the following is an example of natural material?

(a) Plastic
(b) Glass
(c) Wood
(d) Cement
Answer: (c) Wood

Application-Based Questions

Q21. A shopkeeper wants to store pickles. Suggest suitable material for the container and give reasons.

Answer: The shopkeeper should use glass or ceramic containers because:

• Glass is non-reactive with acidic pickles
• It is transparent, allowing visual inspection
• It doesn't absorb odors or flavors
• Easy to clean and sterilize
• Opaque ceramic can be used if sunlight protection is needed

Metal containers should be avoided as pickle acids can corrode metal.

Q22. Why are electric wires coated with plastic or rubber?

Answer: Electric wires are coated with plastic or rubber because:

• Plastic and rubber are insulators they don't conduct electricity
• This prevents electric shocks when we touch the wire
• It prevents short circuits when wires touch each other
• The inner metal (copper/aluminium) conducts electricity while the outer coating ensures safety

Q23. Explain why we can see fish in a clean aquarium but cannot see them clearly in muddy water.

Answer:

• Clean aquarium water is transparent it allows all light to pass through, so we can see fish clearly
• Muddy water is translucent suspended mud particles scatter light, allowing only some light to pass through, making fish appear blurry or invisible
• This demonstrates the difference between transparent and translucent materials

10. Chapter Summary

Concepts Overview

Classification of Objects:

• Objects are sorted into groups based on similar properties
• Main classifications: Living vs Non-living, Plants vs Animals
• Non-living objects classified by material, use, properties

Materials:

• Matter from which objects are made
• Two types: Natural (wood, cotton, gold) and Man-made (plastic, glass, cement)
• Same object can be made from different materials
• Same material can make different objects

Properties of Materials:

1. Appearance (Lustre)
   • Lustrous: Metals (gold, silver, iron)
   • Dull: Non-metals (wood, paper, plastic)
2. Hardness
   • Hard: Iron, stone, diamond, glass
   • Soft: Sponge, cotton, butter, chalk
3. Solubility
   • Soluble in water: Salt, sugar, glucose
   • Insoluble in water: Sand, oil, chalk powder
4. Density
   • Heavier than water (sink): Iron, stone, glass
   • Lighter than water (float): Wood, cork, wax
5. Transparency
   • Transparent: Clear glass, water, air
   • Translucent: Ground glass, butter paper
   • Opaque: Wood, metal, brick

Why Classification Matters:

• Easier to locate and organize materials
• Better understanding of material properties
• Helps choose appropriate materials for specific purposes
• Systematic organization of knowledge

Quick Reference: Properties Table

Property	Type 1	Type 2	Type 3
Appearance	Lustrous (metals)	Dull (non-metals)	-
Hardness	Hard (iron, stone)	Soft (sponge, butter)	-
Solubility	Soluble (salt, sugar)	Insoluble (sand, oil)	-
Density	Heavier (sink)	Lighter (float)	-
Transparency	Transparent (glass)	Translucent (ground glass)	Opaque (wood)

Conclusion

Sorting materials into groups is a fundamental concept in science that helps us understand the world around us. By learning to classify objects and materials based on their properties, students develop critical thinking and observation skills essential for scientific study. The properties discussed - appearance, hardness, solubility, density, and transparency - form the basis for understanding material science in higher classes.

Remember: Every material has unique properties that make it suitable for specific purposes. Understanding these properties helps us make informed choices in daily life, from selecting cooking utensils to choosing construction materials.

Note: These notes are prepared as per CBSE Class 6 Science notes curriculum and NCERT guidelines. For official content, always refer to the latest NCERT textbooks and CBSE notifications.