Materials Around Us
Everything around us is made of some material. This Class 6 Curiosity chapter looks at the difference between objects and materials, the properties we use to describe materials — such as appearance, hardness, solubility, floating and transparency — and how we group materials by these properties.
Learning objectives
- Distinguish an object from the material it is made of.
- Describe properties used to group materials.
- Test materials for solubility and floating.
- Group materials by their properties.
Key concepts
Objects and materials
An object is a thing, while the material is what it is made of. A chair is an object that may be made of wood, plastic or metal. The same object can be made from different materials, and the same material can be used to make many different objects.
Properties of materials
Materials are described by their properties. Some have lustre (shine), like metals, while others are dull. Some are hard, like iron, and others soft, like cotton. Some are rough and some smooth, and some are transparent (you can see through), translucent (partly), or opaque (not at all).
Solubility and floating
Two useful tests sort materials further. Some substances dissolve in water (they are soluble, like sugar and salt) while others do not (insoluble, like sand and chalk powder). And when placed in water, some materials float, like wood and thermocol, while others sink, like a stone or an iron nail.
Grouping materials
We group materials by shared properties — for example, all shiny materials, or all materials that float, or all that dissolve in water. Grouping helps us choose the right material for a job and study the huge variety of materials in an organised way.
Key definitions
- Material
- The substance from which an object is made.
- Lustre
- The shine on the surface of a material, as on metals.
- Soluble
- Able to dissolve in a liquid such as water.
- Transparent
- Allowing one to see clearly through it, like clear glass.
Solved examples
Q1. Is salt soluble or insoluble in water?
Solution: Soluble — it dissolves in water.
Q2. Will a piece of wood float or sink in water?
Solution: It floats.
Q3. Name a transparent material.
Solution: Clear glass (you can see through it).
Common mistakes to avoid
- Confusing an object (the thing) with its material (what it's made of).
- Thinking all materials dissolve in water.
- Assuming heavy-looking objects always sink (it depends on the material and shape).
- Mixing up transparent (see clearly) with translucent (see partly).
Materials Around Us — MCQ Quiz
10 questions with instant feedback. Use number keys 1–4 to answer.
The substance an object is made of is its:
Practice questions
Short answer
What is the difference between an object and a material?
An object is a thing; the material is what it is made of.
Give one soluble and one insoluble substance.
Soluble: sugar; insoluble: sand.
What does 'lustre' mean?
The shine on the surface of a material, as seen on metals.
Long answer
Explain the difference between objects and materials, and give examples.
An object is a particular thing we can see or use, while the material is the substance from which that object is made. For instance, a spoon is an object, and it may be made of the material steel, plastic or wood. Importantly, the same object can be made from different materials — chairs can be wooden, plastic or metal — and the same material can be used to make many different objects — plastic is used for bottles, buckets, toys and chairs. Recognising this difference helps us describe and group the things around us.
Describe the properties used to group materials, including solubility and floating.
Materials are grouped by their properties. Appearance varies — some materials have lustre (shine), like metals, while others are dull. Hardness differs — iron is hard, cotton is soft. Surfaces may be rough or smooth, and materials may be transparent (see through clearly), translucent (partly) or opaque (not at all). Two further tests are very useful: solubility, where soluble substances like sugar and salt dissolve in water but insoluble ones like sand do not; and floating, where materials such as wood float on water while a stone or iron nail sinks. Sorting materials by such shared properties lets us study them in an organised way and choose suitable materials for different uses.
HOTS (Higher Order Thinking)
Why is glass chosen for windows rather than wood?
Glass is transparent, so it lets light through and lets us see outside, while wood is opaque and would block the view and light.
A small iron nail sinks, but large iron ships float. How can both be true?
Floating depends not only on the material but on shape; a ship is built hollow so it pushes aside enough water to float, even though iron itself sinks.
Quick revision
Revision notes
- Object = the thing; material = what it is made of.
- Properties: lustre/dull, hard/soft, rough/smooth, transparent/translucent/opaque.
- Soluble (sugar, salt) vs insoluble (sand); float (wood) vs sink (stone).
- We group materials by shared properties.
Key takeaways
- Objects are made of materials; one material can make many objects.
- Materials are described and grouped by their properties.
- Solubility and floating are simple, useful tests.
Frequently asked questions
What is a material?
The substance from which an object is made, such as wood, metal or plastic.
What does soluble mean?
Able to dissolve in a liquid such as water.
What is a transparent material?
One you can see clearly through, like clear glass.