Changes Around Us

Unit 3

Changes Around Us

Learning Objectives

* To recognize and enlist a few changes that  happen in our day-to-day life

* To classify the observed changes as,

• slow  / fast, reversible / irreversible

• physical and chemical changes

• desirable / undesirable, natural / human made

* To explain the process of dissolution

* To distinguish between a solvent and a solute

Observe the pictures in the previous page and fill in the gaps.

What is common in all the above pairs? 

There is change from the initial stage to the final stage. These changes are permanent and irreversible.

Introduction

What is a change?

The process in which something becomes different from what it was earlier? It is the observable difference between initial state and the final state of any substance.

Change is the Law of Nature. In our day to - day life we see many changes around us. Weather changes periodically (daily/ seasonly), Seasons changes periodically. A paper burns readily while it takes a few days for an iron nail to rust. It takes a few hours for milk to turn into curd but vegetables get softened in a few minutes when cooked.

The said changes are accompanied by change in properties like shape, colour, temperature, position and composition. Some changes can be observed while some are not possible to notice.

Can you observe some changes and write about it?

Activity 1:

W hat happens when you blow air into a balloon?

• Is there change in size?

✓  Yes ___ No

• Is there change in shape?

✓   Yes ___ No

• Is there any other change?

The balloon becomes bigger in size. It straightens up and begins to float in the air.