Materials Around Us – Class 6 Science Chapter 6 Notes & NCERT PDF

Introduction

The chapter opens with a verse from the ancient text Rasaratnasamuchchaya:

उपादानं भवेत्तस्या (मूषायाः) मृत्तिका लोहमेव च — The materials used to make the crucible (a vessel to melt substances) are clay and iron.

Ghulan and Sheeta return to class after the summer break with new notebooks and pens. Their teacher, Madam Vidya, asks them how the things they use are similar or different — in shape, colour, feel and weight. This leads to the big idea of the chapter: everything is made of materials, and materials have properties that decide how we use them.

Any substance that is used to create an object is referred to as a material.

Key Concepts

6.1 Observing objects around us

Objects are made of materials like paper, wood, cloth, glass, metal, plastic and clay. One object may use several materials (a pen: plastic, metal, ink) and one material may make many objects (glass: tumbler, window, bottle).

India's pottery history: the earliest pottery in the subcontinent is 7,000–8,000 years old (Lahuradewa in the Ganga plains, Mehrgarh in Baluchistan). The Harappan (Sindhu-Sarasvatī) Civilisation made wheel-turned, red pottery with black designs. Baked clay is called terracotta.

6.2 How to group materials?

Arranging objects into groups on the basis of a common property is called classification.

We choose a material according to its properties and the purpose of the object. A tumbler must hold water — so cloth or paper cannot be used. Different sports balls (tennis, cricket, hand-exercise) are made of different materials because they must bounce differently (Activity 6.4). Kitchens, grocery shops and chemist shops all group items to find them easily.

6.3 Properties of materials

(a) Appearance – lustre

(b) Hardness

(c) Seeing through materials

(d) Solubility in water

Ghulan's mother makes shikanji — sugar and salt disappear in water.

Make your own ORS: 6 teaspoons of sugar + half a teaspoon of salt in 1 litre of boiled and cooled water — used to treat dehydration.

(e) Mass – how heavy or light

Three identical cups filled half with water (A), sand (B) and pebbles (C) are weighed on a balance. The heavier one has more mass. SI unit of mass: kilogram (kg); also gram (g). Write "7 kg", never "7 kgs".

(f) Volume – space occupied

Madam Vidya asks students to sit while bags are on their seats — they can't, because the bags occupy space. Two identical tumblers with different water levels show different volumes of water.

6.4 What is matter?

Anything that occupies space and has mass is called matter.

Water, sand, pebbles, the cup and even air are matter. Materials are types of matter used to make objects.

Ayurveda's classification: the Ashtanga Hridaya describes 20 gunas (ten pairs of opposite properties) such as guru–laghu (heavy–light), hima–ushna (cold–hot), kathina–mridu (hard–soft), sandra–drava (solid–liquid) — an ancient Indian way of classifying matter.

Activities in the Chapter

Key Terms

Real-life Connections

Common Misconceptions

Keep the Curiosity Alive (Exercise Hints)