Introduction
We see many different materials around us in daily life. These materials differ in shape, size, colour, and uses. To study them easily, we group similar materials together. This process is called sorting of materials.
Why Do We Sort Materials?
- To study materials easily
- To identify their properties
- To select the right material for a specific use
Objects and Materials
- Objects are things made for specific purposes.
- Materials are substances from which objects are made.
Example:
- Chair → made of wood
- Bottle → made of glass or plastic
Properties of Materials
Materials are grouped based on their properties.
1. Appearance
- Materials can be lustrous (shiny) or non-lustrous (dull).
- Example:
- Gold – shiny
- Wood – dull
2. Hardness
- Materials may be hard or soft.
- Example:
- Stone – hard
- Cotton – soft
3. Solubility in Water
- Some materials dissolve in water, while others do not.
- Soluble: Salt, sugar
- Insoluble: Sand, chalk
4. Floating or Sinking in Water
- Some materials float on water, others sink.
- Float: Wood, plastic
- Sink: Stone, iron
5. Transparency
Materials can be:
- Transparent – allow light to pass (glass)
- Translucent – allow partial light (butter paper)
- Opaque – do not allow light (wood)
6. Conductors and Insulators
- Conductors allow electricity to pass through them.
- Example: Copper, aluminium
- Insulators do not allow electricity.
- Example: Rubber, plastic
7. Magnetic and Non-Magnetic Materials
- Magnetic materials are attracted by a magnet.
- Example: Iron
- Non-magnetic materials are not attracted.
- Example: Wood, plastic
Advantages of Sorting Materials
- Makes study easier
- Helps in choosing materials for different uses
- Saves time and effort
Important Questions (Short Answers)
1. What is sorting of materials?
Grouping materials with similar properties.
2. Why do we sort materials?
To study and use them easily.
3. What are materials?
Substances from which objects are made.
4. Give one example of an object and the material used to make it.
Table – wood.
5. What is lustre?
The shine on the surface of a material.
6. Name one lustrous material.
Gold.
7. Name one non-lustrous material.
Wood.
8. What is hardness?
Ability of a material to resist scratching.
9. Name one hard material.
Iron.
10. Name one soft material.
Cotton.
11. What does soluble mean?
Ability to dissolve in water.
12. Name one soluble substance in water.
Salt.
13. Name one insoluble substance in water.
Sand.
14. What does transparent mean?
Allows light to pass through.
15. Name one transparent material.
Glass.
16. What are opaque materials?
Materials that do not allow light to pass.
17. Name one translucent material.
Butter paper.
18. What are conductors?
Materials that allow electricity to pass.
19. Name one conductor.
Copper.
20. What are insulators?
Materials that do not allow electricity.
21. Name one insulator.
Rubber.
22. What are magnetic materials?
Materials attracted by a magnet.
23. Name one magnetic material.
Iron.
24. Name one non-magnetic material.
Plastic.