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Everyday maths 1 (Northern Ireland)
Everyday maths 1 (Northern Ireland)

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1.2 Measuring accurately

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
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An illustration of a pen held against a ruler. One end of the pen is level with 0 cm on the scale; the other end is level with 15 cm on the scale.

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 3: 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
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    An illustration of a DVD case held against a ruler. One end of the case is level with 0 cm on the scale; the other end is level with 19 cm on the scale.

    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
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    An illustration of a screw held against a ruler. One end of the screw is level with 0 cm on the scale; the other end is level with 2.5 cm on the scale.

    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
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    An illustration of a screw head held against a ruler. One end of the screw is level with 0 mm on the scale; the other end is level with 5 mm on the scale.

    Figure 4 Measuring a screw head

Answer

  1. The DVD case is 19 cm tall.
    Described image
    Figure 5 Measuring a pen (answer)
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    An illustration of a DVD case held against a ruler. One end of the case is level with 0 cm on the scale; the other end is level with 19 cm on the scale.

    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 (2 one divided by two cm) long. Note here how the measurement is not a whole number. Often items have to be measured very precisely: when this is the case, it may not be appropriate to round off to the nearest centimetre, for instance.
    Described image
    Figure 6 Measuring a screw (answer)
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    An illustration of a screw held against a ruler. One end of the screw is level with 0 cm on the scale; the other end is level with 2.5 cm on the scale.

    Figure 6 Measuring a screw (answer)
  3. The screw head is 5 mm wide.
    Described image
    Figure 7 Measuring a screw head (answer)
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    An illustration of a screw head held against a ruler. One end of the screw is level with 0 mm on the scale; the other end is level with 5 mm on the scale.

    Figure 7 Measuring a screw head (answer)