Visual Aids and Data

Year 9 Power of Speech • Expository • Visuals

A visual aid should do something the voice cannot do as well: show a shape, a relationship, a sequence or a comparison. Too often, slides become a script on a wall. This page covers honest data display, accessible design and the discipline of describing what the audience is seeing.

What visuals are good at

Visual job	Best form	Example
Show a trend	Line graph	Temperature over thirty years.
Compare categories	Bar chart	Enrolments by faculty.
Show parts of a whole	Stacked bar or pie chart (sparingly)	Where a school's energy is used.
Show a process	Flowchart or numbered diagram	How a bill becomes law.
Show location	Map	Where the fires occurred.
Show an object	Photograph or diagram	The parts of a cell.
Show a relationship	Scatter plot	Study time and results.

Choose the visual that fits the question, not the one that looks most impressive. A simple bar chart is often more honest than a dramatic three-dimensional graphic.

Honest graphs

Problem	Why it misleads	Fix
Truncated y-axis	Small differences look huge.	Start at zero where appropriate; label the axis clearly.
Inconsistent scales	Comparisons become meaningless.	Use the same scale across panels.
Missing baseline	The audience cannot judge change.	Show the starting point.
Cherry-picked range	The trend looks different from the full data.	Show the full period or explain the selection.
3D effects	Distorts area and perspective.	Use flat, labelled charts.
Correlation presented as causation	Implies a causal link that the data cannot show.	Say “associated with”, not “caused by”.

Slide design

One idea per slide.
Large text; no more than about six lines.
High contrast; do not rely on colour alone.
Alt text for images, and a spoken description.
Consistent layout and fonts.
No decorative animation or sound unless it serves the explanation.
A title that states the point, not just the topic.

Your slides should not contain your speech. If the audience is reading, they are not listening. Use keywords, images and one clear visual per idea.

Describing a visual aloud

Some audience members cannot see the screen, and everyone benefits from a clear description. Describe the shape and the point before the detail.

Step	Example
Name it	“This is a line graph showing average rainfall from 1990 to 2020.”
Orient it	“The horizontal axis is the year; the vertical axis is millimetres.”
State the pattern	“Rainfall is variable, but the trend is slightly downward.”
Point to the key detail	“The lowest year is 2019, at about 220 millimetres.”
Explain the limit	“One graph cannot show the full picture; local variation is large.”

Do not say “as you can see” and leave it there. If the point matters, say what the audience should see.

Data in a speech

Numbers are hard to hear. Round them where precision is not essential, and give them a comparison the audience can feel.

Hard to hear	Easier to hear	Why
“3,487 students”	“Almost 3,500 students”	Rounded numbers are easier to hold.
“A 0.7 per cent increase”	“About one in every 140 people”	Gives a human scale.
“1.2 million tonnes”	“The weight of about 200,000 cars”	Creates a comparison.
“Statistically significant”	“The difference is unlikely to be chance”	Translates the term.

Always keep the exact figure in your notes so you can answer a question accurately. Rounding is for speech, not for the record.

Accessibility

Need	Adjustment
Vision impairment	Describe every visual; provide large-print or text alternatives.
Colour vision deficiency	Use labels and patterns as well as colour.
Hearing impairment	Provide captions for video; face the audience; repeat questions.
Neurodiversity	Keep slides predictable; limit animation; provide an outline.
Physical access	Ensure the screen, lectern and controls are reachable.
Language diversity	Define key terms; avoid unexplained acronyms.

Technical backup

Have the slides as a PDF on a second device.
Print a handout with the key visuals.
Know how to advance slides without looking at the screen.
Check the projector, cable and remote before the audience arrives.
Have a version of the explanation that works without slides.

Activity: rebuild a misleading graph

Find a graph in a news article or advertisement.
Identify the axis, scale, baseline and source.
Write one sentence describing what the graph actually shows.
Write one sentence describing what it seems to imply.
Redraw it honestly, or explain what is missing.
Practise describing your redrawn graph aloud in thirty seconds.

If the visual needs a paragraph of explanation, it is not doing its job. Simplify the visual or cut it. The speaker should carry the argument; the visual should carry the shape.

Common errors

Reading slides aloud. The audience can read faster than you can speak.
Too much text. It splits attention.
Misleading axes. They damage trust.
“As you can see”. Say what they should see.
No backup. Technology fails; the explanation should not.
Ignoring access. A visual that excludes people is not effective communication.

Next, study demonstrating a process to combine speech, action and equipment. The questioning and clarity page shows how to check that the visual worked.