Chapter 6: Materials Around Us-Chapter Review Science Curiosity Class 6 In English

Chapter 6: Materials Around Us

Everything around us is made of one or more materials. A chair may be made of wood, a bottle may be made of plastic, and a tumbler may be made of glass or steel. Different materials have different properties, and these properties determine how they are used in our daily life. This chapter introduces students to the concept of materials, their classification, their physical properties, and the idea of matter.

Introduction

We use countless objects every day, such as books, pencils, utensils, clothes, furniture, toys, bottles and electronic devices. Although these objects look different, each of them is made from one or more materials like wood, metal, glass, paper, plastic, rubber, cotton or clay. Understanding the properties of materials helps us choose the right material for making a particular object.

What is a Material?

A material is any substance that is used to make an object. An object may be made from a single material or from several different materials. For example, a pen is made from plastic, metal and ink, while a notebook is made from paper and cardboard.

Classification of Materials

Materials can be grouped or classified based on their common properties. Classification makes it easier to study, compare and understand different materials. The same material can be used to make many different objects, and one object can also be made from different materials depending on its purpose.

Properties of Materials

1. Appearance (Lustre)

Some materials have a shiny surface and are called lustrous materials. Most metals such as iron, copper, aluminium and gold show lustre. Materials like paper, wood, rubber and jute do not shine and are called non-lustrous materials.

2. Hardness

Some materials are difficult to scratch or compress and are called hard materials, while others can be scratched or compressed easily and are called soft materials. For example, stone and iron are hard, whereas sponge, cotton and rubber are comparatively soft.

3. Transparency

Materials differ in the amount of light they allow to pass through them.

• Transparent materials allow light to pass completely, making objects visible clearly. Examples include glass, clean water and air.
• Translucent materials allow only some light to pass through them, making objects appear blurred. Examples include butter paper and frosted glass.
• Opaque materials do not allow light to pass through them. Examples include wood, cardboard and metals.

4. Solubility in Water

Some materials dissolve completely in water and are called soluble substances. Sugar and salt dissolve in water, whereas sand, chalk powder and sawdust do not dissolve and are called insoluble substances.

5. Mass

Every material has mass. Heavy objects have more mass, while lighter objects have less mass. The SI unit of mass is kilogram (kg), whereas gram (g) is commonly used for smaller quantities.

6. Volume

Every material occupies space. The space occupied by a material is called its volume. Liquids are commonly measured in litre (L) and millilitre (mL).

Matter

Anything that has mass and occupies space is called matter. All materials around us are examples of matter. Air, water, stone, wood, paper, plastic and metals are all forms of matter because they have mass and occupy space.

Importance of Classification

Grouping materials according to their properties helps scientists and students understand similarities and differences among substances. Classification also helps in selecting suitable materials for different purposes, such as making utensils, furniture, buildings, clothes and sports equipment.

Applications in Everyday Life

• Selecting suitable materials for household objects.
• Making safe cooking utensils.
• Choosing transparent materials for windows.
• Using waterproof materials for raincoats and umbrellas.
• Preparing solutions such as ORS and lemonade by dissolving substances in water.
• Manufacturing sports equipment according to required properties.

Learning Outcomes

• Understand the meaning of materials and matter.
• Identify different materials used in daily life.
• Classify materials on the basis of their properties.
• Differentiate between lustrous and non-lustrous materials.
• Differentiate between hard and soft materials.
• Differentiate between transparent, translucent and opaque materials.
• Identify soluble and insoluble substances.
• Understand the concepts of mass and volume.
• Relate material properties to their practical uses.

Chapter Highlights

• Every object is made from one or more materials.
• Materials are selected according to their properties and intended use.
• Materials can be classified based on appearance, hardness, transparency, solubility, mass and volume.
• Lustrous materials usually include metals.
• Transparent materials allow light to pass completely.
• Sugar and salt are soluble in water, whereas sand and chalk powder are insoluble.
• Mass is measured in kilograms (kg) and grams (g).
• Volume is measured in litres (L) and millilitres (mL).
• Anything that occupies space and has mass is called matter.
• Classification helps us understand and use materials effectively in everyday life.