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Science Class 6 - Changes Around-Us Notes

Comprehensive study notes for Class 6 - Changes Around-Us olympiad preparation

Changes Around Us

Welcome to the chapter on Changes Around Us for Class 6. In this chapter, you will learn about different types of changes that happen in our surroundings, why they occur, and how they affect our lives. By the end of this chapter, you will be able to identify and explain various changes you see every day!

Introduction

Changes are happening all the time around us. Some changes are fast, some are slow. Some changes can be reversed, while others cannot. Let’s explore the different types of changes and their causes!

Types of Changes

  • Physical Changes: Changes in shape, size, or state. Example: Melting ice, tearing paper.
  • Chemical Changes: Changes that create new substances. Example: Rusting iron, burning wood.
  • Reversible Changes: Changes that can be undone. Example: Freezing water to make ice, then melting it back to water.
  • Irreversible Changes: Changes that cannot be undone. Example: Cooking food, burning paper.

Examples of Changes Around Us

  • Day changes to night.
  • Leaves change color and fall in autumn.
  • Water boils and turns into steam.
  • Milk turns sour if left outside.
  • Seeds grow into plants.

Why Do Changes Happen?

  • Changes can happen because of heat, light, pressure, mixing, or time.
  • Some changes are natural, like seasons changing.
  • Some changes are caused by humans, like cooking food or building houses.

Fun Activity: Observe and Record!

Look around your home or school. Write down three changes you see in a day. Are they reversible or irreversible?

Summary

  • Changes are happening all around us.
  • Some changes can be reversed, some cannot.
  • Physical changes do not make new substances, chemical changes do.

Practice Questions

  1. Give two examples of reversible changes.
  2. Name one chemical change you see at home.
  3. Is melting ice a physical or chemical change?
  4. Why does milk turn sour?
  5. Can you reverse the change when paper is burnt?

Challenge Yourself

  • List three changes that happen in nature and say if they are reversible or irreversible.
  • Try to reverse a change at home (like melting and freezing water).

Did You Know?

  • Rusting is a slow chemical change that happens to iron when it gets wet.
  • Cooking is an irreversible change because you cannot get the raw food back!

Glossary

  • Physical Change: Change in shape, size, or state without making a new substance.
  • Chemical Change: Change that makes a new substance.
  • Reversible: Can be changed back.
  • Irreversible: Cannot be changed back.

Answers to Practice Questions

  1. Melting ice, dissolving sugar in water.
  2. Cooking food, rusting iron.
  3. Physical change.
  4. Because of bacteria and chemical change.
  5. No, burning paper is an irreversible change.

Notice the changes around you and think about why they happen!

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