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Everyday maths 1
Everyday maths 1

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1 Using metric measurements

So what do you use to measure things? If you were to measure something small, such as a grain of rice, you would probably use a ruler. To measure something bigger, like the length of a room or garden, you would probably use a tape measure.

You could try estimating the size of something before measuring it, which would help you to decide what tool you need to measure it. If you wanted to measure the walls of a room before redecorating, you’d get a more accurate measurement using a tape measure rather than a 30-centimetre ruler! After you’ve made an estimate you can check how accurate it is by measuring the object.

How long is a pen? Find a pen, make an estimate of how long you think it is and then measure it accurately using a ruler. To measure accurately, line up one end of the pen with the 0 mark on the ruler. If there is no 0 mark, use the end of the ruler. Hold the ruler straight against the pen. Which mark does the other end come to?

Hint: Be careful with the bit of ruler or tape measure that comes before the first mark! Make sure you line up whatever you’re measuring with the ‘zero’ mark.

Described image
Figure 1 Measuring a pen

You can see from this diagram that the pen is 15 cm long.

Now try the following activity. Remember to check your answers once you have completed the questions.

Activity 1: Building a shelf for DVDs

  1. You want to build a shelf to hold some DVDs. You need to make sure that it’s big enough! How tall is a DVD case?
    Described image
    Figure 2 Measuring a DVD case
  1. You have run out of screws. Before you go to buy some more, you need to measure the last screw you have to make sure you buy some more in the same size. How long is this screw?
    Described image
    Figure 3 Measuring a screw
  1. How far is it across the head of the screw?

    Hint: Draw lines from the edge of the screw head down to the ruler to help you measure it.

    Described image
    Figure 4 Measuring a screw head

Answer

  1. The DVD case is 19 cm tall.
    Described image
    Figure 5 Measuring a pen (answer)
  2. The end of the screw is halfway between 2 and 3 cm, so the screw is 2.5 cm long.
    Described image
    Figure 6 Measuring a screw (answer)
  3. The screw head is 5 mm wide.
    Described image
    Figure 7 Measuring a screw head (answer)