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Reading and Literature Studies · Reading Informational and Graphic Texts

Reading Infographics and Data Graphics Critically: Axes, Icons, Samples and Causation

2.2 1.7 1.3About 70 minutes
Learning goals
  • I can read a graphic in a careful order: title, source, axes and units, data, what is missing.
  • I can recognize truncated axes, area tricks, cherry-picked ranges and correlation presented as causation.
  • I can calculate how much a distortion exaggerates a change.
  • I can evaluate an infographic's credibility using evidence from its features.

Words to know

infographic
A graphic text that combines images, data and short text to present information quickly.
truncated axis
A graph axis that starts above zero, which can exaggerate differences.
sample
The group of people or things actually measured or surveyed.
representative sample
A sample that reflects the larger group it is meant to describe.
correlation
A relationship in which two variables change together.
causation
A relationship in which one thing makes another happen.
cherry-picking
Selecting only the data that support a claim and leaving out the rest.

Hook: the chart that lied without lying

A politician holds up a bar chart. One bar is three times as tall as the other. Look how much things have improved! the politician says. Every number on the chart is true. But the change is actually about 4 percent. How? The vertical axis didn't start at zero. Graphic texts can mislead without a single false number, which is why reading them critically is a Grade 11 skill.

Remember from Grade 10

In ENG2D you read infographics and charts for their main ideas and explained how text features help meaning, and you checked sources with CRAAP and lateral reading. This lesson adds the tools to evaluate the graphics themselves: axes, scales, chart choice, sample size, and the difference between correlation and causation.

Read a graphic in this order

  1. Title and headline: what does it claim? A headline is often an argument, not a neutral description.
  2. Source and date: who made it, from what data, when? Who paid for it?
  3. Axes, units and scale: what is measured, in what units, starting where?
  4. The data: now look at the bars, lines or slices.
  5. What is missing: sample size, time period, comparison group, margin of error.

Choosing the right chart

  • Bar chart: comparing amounts across categories.
  • Line graph: change over time.
  • Pie chart: parts of one whole (slices must add to 100%).
  • Scatter plot: the relationship between two variables.
  • Map: patterns by place.

A chart type that does not fit the data is a warning sign.

Four common distortions

  1. Truncated axis: the vertical axis starts well above zero, so small differences look huge.
  2. Area and 3D tricks: an icon doubled in height and width has four times the area; a tilted 3D pie makes front slices look bigger.
  3. Cherry-picked range: showing only the years that support the claim.
  4. Correlation presented as causation: two things rising or falling together does not prove one causes the other.
A: axis starts at 4,7004,7004,8004,9005,00020254,80020265,000B: axis starts at 001,0002,0003,0004,0005,00020254,80020265,000Same data: average daily bus riders. Real increase: 200 riders, about 4%.
The same two numbers, drawn twice. In A, the axis starts at 4,700, so the 2026 bar looks three times as tall. In B, starting at 0, the bars are almost equal, which is honest: the increase is 200 riders out of 4,800, about 4%.
Misleading: doubled height AND width2024: 10 t2026: 20 tThe 2026 bin looks 4× bigger (area × 4).Honest: one icon = 10 tonnes2024: 10 t2026: 20 tTwo equal icons: correctly twice as much.
Recycling collected doubled from 10 to 20 tonnes. On the left, the bigger bin is twice as tall and twice as wide, so it has four times the area and looks like a fourfold increase. On the right, two equal icons show the doubling honestly.
Worked example

Let's calculate what a truncated axis hides

In chart A, how tall do the bars look compared with each other, and what is the real percent increase?

  1. Apparent size: the axis starts at 4,700. The 2025 bar shows 4,800 − 4,700 = 100 units of height; the 2026 bar shows 5,000 − 4,700 = 300. So 2026 looks 3 times as tall.
  2. Real change: 5,000 − 4,800 = 200 riders.
  3. Percent increase: 200 ÷ 4,800 ≈ 0.0417, about 4.2%.
  4. Conclusion: the chart turns a 4% increase into what looks like a 200% increase. A truncated axis is sometimes acceptable (for example, to show small changes in temperature), but it should be clearly marked, and the reader must check it.

The bars look 3× different, but ridership grew only about 4%. Always read the axis before the bars.

An infographic to evaluate

Imagine this infographic is shared on social media by an invented company, FocusBand, which sells a wristband that buzzes when you pick up your phone.

HEADLINE: Phones Are Destroying Teen Grades

  • A line graph titled Average grade vs. daily screen hours shows marks falling as screen hours rise. The y-axis runs from 70% to 80%.
  • A large icon: Teens spend 9 hours a day on screens! (no source given)
  • A pie chart, drawn in 3D and tilted, of How teens use phones: social media 45%, video 30%, games 20%, homework 10%.
  • Small print at the bottom: Survey of 50 FocusBand customers. © FocusBand
Worked example

Let's evaluate the FocusBand infographic

Evaluate the infographic's credibility and fairness, using evidence from its graphics and features.

  1. Source and purpose: made by FocusBand, which sells a product that limits phone use. It has a commercial interest in making phones look harmful. This doesn't make it false, but it calls for extra checking.
  2. Sample: 50 FocusBand customers: tiny, and not representative (people who bought an anti-phone gadget may already worry about their phone use). This is in small print.
  3. Line graph: the y-axis runs from 70% to 80%, a truncated axis that makes the decline look steep. More importantly, it shows a correlation (more screen hours, lower marks), but the headline claims causation (destroying). Other factors (sleep, part-time jobs, stress) could explain both.
  4. Big statistic: 9 hours a day has no source and no definition (does it include school computers? TV?).
  5. Pie chart: 45 + 30 + 20 + 10 = 105%, so the slices do not describe one whole. Either respondents could choose more than one answer (so a pie is the wrong chart) or the numbers are wrong. The 3D tilt also distorts the slices.
  6. Overall: the graphics are attention-grabbing but misleading. The infographic is advertising presented as information.

Low credibility: a biased source, a tiny unrepresentative sample, a truncated axis, correlation sold as causation, an unsourced statistic and a pie that adds to 105%.

Just for fun

Ice cream sales and sunburns rise and fall together every year. Nobody has ever been sunburned by a scoop of maple walnut; sunny summer weather drives both. Correlation often has an alibi.

Hands-on activity

Chart doctor

You need: a newspaper, flyer, news website or social-media infographic with at least one chart, graph paper (or plain paper and a ruler), and a calculator.

  1. Find a chart. Read it in order: title, source, axes and units, data, what is missing.
  2. Check for the four distortions: truncated axis, area or 3D tricks, cherry-picked range, correlation as causation. If it's a pie, add the slices.
  3. Redraw the chart honestly on graph paper (axis from zero, equal icons, a neutral title).
  4. Show both versions to someone at home. Ask which seems more dramatic, and which is more accurate.

What to look for: calculations shown; distortions named with evidence; an honest redraw with labelled axes and a source line.

Your turn

1

What is a truncated axis?

2

Bus riders rose from 4,800 to 5,000. What is the percent increase? Show your work.

3

An icon is drawn twice as tall and twice as wide. How many times bigger does its area look?

4

Add the FocusBand pie chart slices. What does the total tell you?

5

Why is a sample of 50 FocusBand customers a weak basis for claims about all teens?

6

What is the difference between correlation and causation?

7

Which chart type is best for showing change over time?

More practice: warm-up

1

What should you read first on any graphic?

2

Which chart shows parts of one whole?

3

Which chart compares amounts across categories?

4

Why check who made an infographic?

5

In chart B, where does the vertical axis start?

More practice: on your own

1

In chart A, explain why the 2026 bar looks three times as tall as the 2025 bar.

2

Rewrite the FocusBand headline so it matches what the data can actually show.

3

Suggest two other factors that might explain why students with more screen time have lower marks.

4

A chart shows a town's crime falling, but only for the three years after a new policy. What distortion might this be, and what would you want to see?

5

Why does the small print © FocusBand matter more than its size suggests?

Challenge

1

A news graphic says Library visits up 50%! Visits went from 2 per day to 3 per day. Is the headline accurate? Is it misleading? Explain.

2

Design an honest version of the FocusBand line graph. List three changes.

3

Evaluate this claim: Truncated axes are always dishonest.

Check your understanding

Quiz

1.

A bar chart's axis starts at 4,700. Bars show 4,800 and 5,000. The 5,000 bar looks...

2.

Riders rose from 4,800 to 5,000. The percent increase is about...

3.

Doubling an icon's height and width makes its area...

4.

A pie chart's slices add up to 105%. This means...

5.

Students with more screen time have lower marks, so screens cause low marks. This reasoning confuses...

6.

Which chart type best shows change over time?

7.

Which detail most weakens the FocusBand infographic's credibility?

For parents and teachers

What this lesson teaches: ENG3U Reading 2.2 (text features of graphic texts: titles, axes, sources, icons), 1.7 (evaluating the effectiveness and reliability of a text) and 1.3 (identifying the main ideas and supporting data in graphics).

How to help at home:

  • When a chart appears on the news or in a flyer, ask: Where does the axis start? Who made this?
  • Do the math together: a 50% rise from 2 to 3 is still only 1.

Common difficulties:

  • Reading bars before axes. Train the order: title, source, axes, data.
  • Accepting causation claims. Ask: What else could explain this?
  • Percentages without base numbers. Always ask: percent of what?

Facts used: all data (bus riders, recycling tonnes, FocusBand, its survey) are invented for this lesson. The ice cream and sunburn example illustrates correlation without causation: both rise in sunny summer weather.