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Basic 3 · Science · Materials

Why Objects Are Made of Different Materials

In this topic you will explain why the same object can be made of different materials and choose the best one.

By the end of these notes you should be able to:

  • Show that one object can be made of different materials
  • Compare which material works best
  • Test materials for a job

What you already know

  • Objects made of one or more materials

Copy everything that has a blue line on its left into your notebook. The other parts are for reading.

Strand
Diversity Of Matter
Sub-strand
Materials
Indicator
B3.1.2.1.2 – Demonstrate understanding that an object is made of one or more materials

Introduction

Cups can be made of glass, plastic, metal or clay. Which is best for a small child? Which is best for hot tea?

1. Same Object, Different Materials

Cups made of different materials
MaterialGood pointProblem
glasseasy to see the drinkbreaks easily
plasticlight, does not break easilycan melt with very hot drinks
metalstronggets hot to hold
claykeeps water coolcan crack
A glass cup, plastic cup, metal cup and clay cup
Figure 1: Cups made of different materials Draw two cups and write one good point of each material.Illustration: Sirbus

2. A Fair Test

Which material soaks up water best?

  1. Cut equal pieces of cloth, paper and plastic.
  2. Pour the same amount of water on each.
  3. See which piece soaks up the most.

Cloth and paper soak up water. Plastic does not.

New words

compare
To see how things are alike or different.
test
To try something to find out.
fair test
A test where only one thing changes.
absorb
To soak up.

Summary

  • One object can be made of different materials.
  • Each material has good points and problems.
  • A fair test helps us choose the best material.

Class activity: Soak Test

  1. Do the soak test with cloth, paper and plastic.
  2. Record which absorbs water.
  3. Choose the best material for wiping a table.

You need: Wood offcut, Metal spoon, Clear plastic bottle

Exercises

Answer in your exercise book first, then check your answers.

  1. 1. Which cup breaks most easily?

    • A. Glass
    • B. Plastic
    • C. Metal
    • D. Rubber
    Show answer
    Answer: GlassGlass is brittle.

  2. 2. Which material absorbs water?

    • A. Cloth
    • B. Plastic
    • C. Metal
    • D. Glass
    Show answer
    Answer: ClothCloth soaks up water.

  3. 3. Cups can be made of clay.

    • A. True
    • B. False
    Show answer
    Answer: TrueClay pots and cups are common.

  4. 4. In a fair test, we change everything at once.

    • A. True
    • B. False
    Show answer
    Answer: FalseOnly one thing changes.

  5. 5. To soak up is to ______.

    Show answer
    Answer: absorbThat is absorbing.

  6. 6. Which cup material is best for a young child and why?

    Show answer
    Answer: Plastic, because it does not break easily.Safety matters.

Homework

  1. Test three materials at home to see which one soaks up water.