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Lesson · Grade 10 · Workplace Mathematics

Choosing the right graph for the data

  • Grade 10
  • Workplace Mathematics
  • 1 min 56 s
  • British Columbia
  • BC10-MA-43

Four data sets are each matched with their graph: a week of noon temperatures with a line graph, favourite sports with a bar graph, a monthly budget with a circle graph and the heights of 30 people with a histogram. Along the way, two wrong matches show why the choice matters: a circle graph hides the rise in temperature, and a line drawn through sports that have no order seems to fall or rise depending only on how the bars are arranged.

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In one sentence

The question this lesson answers

Here are four data sets. Which kind of graph fits each one?

First, the temperature at noon each day for one week.

Transcript

What the lesson says

Here are four data sets. Which kind of graph fits each one?

First, the temperature at noon each day for one week.

Change over time suits a line graph: points joined in day order show the trend, from 12 up to 19 degrees.

Now a wrong match. A circle graph, or pie chart, shows parts of one whole.

It fails: the total, 108 degrees, is not a whole of anything, and the slices hide the rise.

Next, 25 students chose a favourite sport. Each sport is a category: a group with no order.

To compare categories, use a bar graph: one bar per sport, with gaps between them.

A common mistake is a line graph. It suggests a fall from soccer to swimming.

But reorder the sports, and the same data seems to rise. The line means nothing here.

Third, a monthly budget: rent, food, transport and savings.

Parts of a whole suit a circle graph. The shares add to 100 per cent, and rent's 50 per cent fills half the circle.

Last, the heights of 30 people, in intervals: ranges 10 centimetres wide.

Data in intervals suits a histogram. Each bar's height is the frequency: the count in that interval.

The bars touch, as the intervals meet with no gaps. The counts add to 30.

Change over time, line graph. Categories, bar graph. Parts of a whole, circle graph. Data in intervals, histogram.

Ask what kind of data you have, then pick the graph made for it.

Curriculum

Where this fits

British Columbia, Grade 10

Workplace Mathematics 10, Data and probability: create, interpret, and critique graphsBC10-MA-43

Next: Histograms: bars for ranges of numbers

The outcomes and strands follow the British Columbia curriculum.

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