A graph can look completely obvious to its creator and still be inaccessible to a classmate who cannot see it, reads it on a small screen, or receives a poor printout. A description that says ‘the graph goes up’ may not solve the problem.
A useful graph text description is a concise explanation of what a chart measures, its axes or categories, the key numerical values, and the comparison the reader needs to understand. For a complex chart, provide a short identifying alternative and a nearby longer description or data table that conveys the essential information.
Start with the question the chart was made to answer
Before writing, identify the chart type, time period or groups, measurement unit, scale and reason for comparison. Then verify each number directly against the source table. Accessibility is not a licence to smooth out an awkward trend or supply conclusions that the data never established.
Imagine a bar chart called ‘Books Borrowed from the Class Shelf’. Its horizontal categories are September, October and November. Its vertical axis shows number of books borrowed, with values 12, 18 and 15. These are invented classroom numbers for a teaching exercise, not an actual school’s lending record.
Worked example: short label, then meaningful detail
A weak label is: ‘Graph showing books’. A better short alternative is: ‘Bar chart of class-shelf book loans in September to November; October is highest.’ That identifies the chart and its main point, but it does not fully replace the data.
A useful accompanying text reads: ‘The bar chart shows books borrowed from the class shelf each month: 12 in September, 18 in October and 15 in November. October had six more loans than September, while November had three fewer than October. These are monthly borrowing counts, not numbers of unique pupils.’
- Check every number: September 12, October 18, November 15.
- Check comparisons: 18 − 12 = 6 more in October than September; 18 − 15 = 3 fewer in November than October.
- Check the category and unit: the values are numbers of borrowing transactions or books borrowed according to the stated record, not a measure of reading comprehension.
- Keep the full underlying data available in a table if the reader needs exact values for their own comparison.
A teacher may wish to add that the number of books borrowed in October was 50% higher than September: 6 ÷ 12 × 100 = 50%. That percentage is correct with September as the comparison base. However, avoid adding it if the learning purpose is simply to report counts; more calculations do not automatically make a description clearer.
Diagnose common accessibility and reasoning mistakes
Do not rely on colour alone: ‘the blue bar wins’ fails when colour is unavailable, and ‘wins’ is usually an inaccurate description of a count. Do not claim ‘students read more in October’ when the chart records loans, not reading completion. Do not omit units, dates or the fact that a non-zero axis baseline can visually exaggerate differences.
The World Wide Web Consortium’s guidance for complex images explains why informative charts may need both a short alternative and a longer description. A full table placed in nearby text is often more helpful than packing every number into a single overloaded image label.
Practice that moves towards independence
- Guided: describe the three-month bar chart using the categories, counts and two correct comparisons.
- Paired: ask a partner to hide the chart and reconstruct its data table only from your words. Compare the reconstructed table with the original.
- Independent: choose a different class graph with at least four categories, write the short alternative and separate data description without a model.
- Transfer: use the same method for a line graph by naming the axes, units, dates, key changes and any gaps rather than only describing its shape.
What parents and teachers can check
A helpful diagnostic is to remove the image temporarily and ask whether the learner can still answer the graph’s original question. Observable progress is when the learner stops saying ‘as you can see’ and begins naming evidence, comparison bases and limits accurately. Peers can give precise feedback on a missing unit or unsupported conclusion without rewriting the child’s work.
For adjacent skills, read making a presentation slide understandable without its speaker and repairing a graph legend after changing colours. Both concern communication, but a text alternative addresses a reader who may not have access to the visual at all.
Limits and FAQs
FAQ: Is one-sentence alt text always enough? Not for a graph with many meaningful values or relationships; a longer description or accessible table may be necessary. FAQ: Should the text repeat the entire nearby table? Not necessarily, if the table already provides the same information and the short alternative points readers to it. FAQ: Can the description include a conclusion? Yes, if the chart supports it and the wording distinguishes observation from interpretation.
This practice is about more than compliance. Describing data in words tests whether the learner truly knows what the graph means. Explore the eduKate Education Hub and the Clementi learning reference for the wider habit of observing, explaining, practising and checking. The simplest test is powerful: could a classmate answer the original question without seeing the picture?