Some Basic Questions about PowerPoint Slides

Wide shot of a university classroom in which a male professor lecture with PowerPoint slides

If a visitor from another planet dropped in to observe teaching in North America (maybe other places as well), they’d likely conclude that teaching could not occur without PowerPoint slides. And they’re not just in classrooms; they’re part and parcel of all kinds of professional presentations. Without question, they’re superior to their predecessors: overhead projectors and slide carousels. But when something is used this routinely, it often happens without a lot of thinking. For that reason, it may be time to revisit some PowerPoint fundamentals, and I’d like to do that with a few basic questions.

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Does PowerPoint work equally well in every field, for all kinds of content? Do we see more of it in some courses and less of it in others? Is that what we should expect? Some things we teach can’t be seen with the naked eye. Those are the cases when the picture is worth far more than 1,000 words. Visual representations of abstractions are also helpful, and it’s easier to see how things relate than to hear about connections. Visuals make many things easier to understand, but do they expedite the understanding of everything? What if the picture is unrelated or only loosely connected to the content?

It’s also quite common for text to accompany the visuals on a PowerPoint slide. Dual coding theory predicts that’s a problem. Slides with both pictures and words require different kinds of mental processing. Then there’s the fact that while the slide is up, the teacher is usually talking. There’s a cognitive overload, so none of the information gets fully processed. Findings in a two-part study involving biology students considered whether PowerPoint treatment with visuals better promoted learning than slides with visuals and text (Smith-Peavler, Gardner, & Otter, 2019). The researchers found that on average, exam scores were 5.73 percent higher when students were taught with image-only slides.

Are PowerPoint slides more useful at some course levels than at others? Do beginning students need them more than seniors? This same study surveyed nearly 600 students enrolled in an introductory, a second-level, or a senior biology course. Students in all three courses rated PowerPoint slides as a useful and effective tool for their learning. But students in that first course rated them significantly higher than those in the senior course did. To what might those differences be attributed? Are there reasons to decrease dependence on slides?

Do PowerPoint slides work better for some students than for others? If students are taking notes, typically they copy the text from the slides. One wonders whether the affinity students feel toward PowerPoints isn’t related to their not having to decide what to write down. Copying does get accurate information in their notes. It doesn’t automatically trigger the kind of mental processing necessary to understand what they wrote down. Students responding to survey questions in the first of these two studies indicated that they wanted text on the slides, even though the second study revealed that the presence of both text and visuals resulted in lower exam scores.

Are some ways of using PowerPoint more effective than others? Some answers here are obvious. If the slide isn’t up there long enough, it’s frustrating, and it compromises the value of what’s on the slide. With lots of content to cover, there’s a tendency to put too much material on the slides—too much to read, copy, or comprehend. With so much to cover, there’s also a strong need to keep talking about it. Students are likely attending to one or the other; chances are it’s the slide. Either way, content is not getting covered.

Effective use involves asking how many slides are enough. More bluntly stated, should PowerPoint slides be used every day, in every course? Their ubiquity creates the expectation that teachers will provide them. Students start believing they can’t succeed without them, and they aspire to download the complete set. Is that a good way to support students’ learning efforts?

There’s research that addresses (rather than definitively answers) most of these questions. The study referenced here includes a good bibliography. One of the clearest findings is that the answers aren’t the same for everyone. Have you thought about what the answers might be for you—in your courses and for your students?


Smith-Peavler, E., Gardner, G. E., & Otter, R. (2019). PowerPoint use in the undergraduate biology classroom: Perceptions and impacts on student learning. Journal of College Science Teaching, 48(3), 74–83.

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