Apply Mayer's multimedia principles to redesign a text-heavy slide and write a useful handout.
Why it matters
Slides are the most common training material and the most commonly misused. A slide packed with text turns the trainer into a narrator and the learners into readers who are also trying to listen, which is the worst of both. Research on multimedia learning gives clear rules for slides and handouts that support learning instead.
Mayer's cognitive theory of multimedia learning
Richard Mayer and colleagues have run hundreds of experiments on learning from words and pictures, summarized in Multimedia Learning and, with Ruth Clark, e-Learning and the Science of Instruction. The theory rests on three ideas:
- Dual channels: we process visual/pictorial and auditory/verbal information in partly separate channels.
- Limited capacity: each channel can handle only a little at a time (working memory again).
- Active processing: learning happens when people select, organize and integrate information with what they know.
From this come design principles. The most useful for slides:
| Principle | Rule | Slide example |
|---|---|---|
| Multimedia | Words and relevant pictures beat words alone | A branch diagram, not just bullet text |
| Coherence | Cut interesting but irrelevant material | Remove stock photos, decorative icons, background music |
| Signaling | Highlight the essential organization | Bold the one command that matters; use a consistent heading |
| Redundancy | Do not add on-screen text that repeats narration word for word | Short labels on screen, explanation spoken |
| Spatial contiguity | Put words next to the part of the picture they describe | Labels on the diagram, not in a legend |
| Temporal contiguity | Present words and matching pictures at the same time | Show the diagram while explaining it, not three slides later |
| Segmenting | Break complex lessons into learner-paced parts | One step per slide in a process |
| Pre-training | Teach key terms first | A vocabulary slide before the process |
Note the redundancy principle carefully: it is about narration plus identical on-screen text. Short key phrases with a spoken explanation are fine. And slides you send as a self-study handout have different needs from slides you present, which is why many trainers make two versions.
Redesigning a text-heavy slide
Before (title: "Branching"):
- A branch is a pointer to a commit in the repository history
- When you create a branch, Git creates a new pointer at the current commit
- Commits made on the branch move the pointer forward
- HEAD indicates the currently checked-out branch
- Use
git switch -c <name>to create a branch - Merge the branch back when the feature is done
- Delete merged branches to keep the repo tidy
After, split into three slides:
- Title as a sentence: "A branch is a movable label on a commit." A diagram of commits as circles,
mainandfix-loginas labels, with the labelHEADattached tofix-login. Trainer explains verbally. - "New commits move the current branch forward." The same diagram with one new circle,
fix-loginmoved onto it,mainunchanged. - "Create and switch in one command." Just
git switch -c fix-loginin large monospace text.
The rest of the bullets go into the handout, written in full sentences for later reference. Writing slide titles as full-sentence claims (sometimes called the assertion-evidence approach, researched by Michael Alley and colleagues in engineering education) tells learners the point of each slide before they look at the picture.
Handouts that teach
A good handout is not a printout of the slides. Useful formats:
- Worked example sheet with subgoal labels (from the cognitive load lesson).
- Job aid or cheat sheet: the five commands they will use daily, with when to use each.
- Guided notes: a skeleton with gaps learners fill in during the session, which adds a little retrieval.
- Reference with the detail you cut from slides.
Practical rules
- Font large enough to read from the back (or on a laptop in a video call): 24 pt minimum for body text is a common rule.
- Code in monospace, high contrast, and only the lines that matter.
- One idea per slide; more slides is fine.
- Check color contrast (aim for at least 4.5:1, the WCAG level for normal text) and never use color alone to carry meaning.
- Use the slide software's built-in layouts and reading order so screen readers handle it.
Common mistakes
- Using the slide as your speaker notes.
- Decorative images and animations that add extraneous load.
- Reading the slide aloud word for word.
- A tiny screenshot of a full IDE when one line matters; crop and zoom instead.
Quick recap
- People learn better from words plus relevant pictures, with clutter removed.
- Do not duplicate narration as on-screen text; put labels next to what they describe.
- Split dense slides; use sentence titles and simple diagrams.
- Handouts are separate tools: worked examples, job aids, references.
Try it
On the Do tab, redesign a text-heavy slide using these principles.