Why your students forgot everything about your PowerPoint slides
Don’t worry, we’ve all been there – you wake up late the night before Thursday and have to teach at 8am the next day. So what are you doing? Throw some text on a PowerPoint and get ready to talk about your points. It couldn’t hurt, could it? You might not always read straight from the slides, they will just help keep your course on track, and if you lose your spot, the text is there for you.
Unfortunately, whether you are discussing Columbus with 4th grade students or quantum physics with freshmen, you may be hurting your students’ learning more than helping them.
Let’s take a look at why instructional design typically doesn’t work with students, or anyone learning for that matter, when teaching with PowerPoint, and how you can avoid it. It all starts with a little concept called “cognitive load”.
Too much for the student to deal with
Imagine your student’s brain as a container. As you start to throw stones into the container, they become heavier and heavier and more difficult for the student to transport or sort. Basically, it’s the cognitive load. Cognitive load describes the ability of our brain’s working memory (or WM) to store and process new information. We all have a limited amount of working memory, so when we have to manage information in multiple ways, our load becomes heavier and more and more difficult to manage.
In a classroom, a student’s cognitive load is greatly affected by the ‘foreign’ nature of information, that is, the way information is presented to them (Sweller, 2010). Every teacher instinctively knows that there are better and worse ways to present information. The reason is, according to research, that when you lighten the load, it is easier for students’ brains to take in information and turn it into memory.
Teaching with text-based PowerPoint slides while reading them aloud, unfortunately, is throwing too many stones in the student container – and potentially turning students back.
The redundancy effect
Simultaneous auditory (oral) and visual presentation of text, often done through PowerPoint presentations, is all too common in classrooms today. Think about it: how many times have you walked into a classroom or boardroom and heard a teacher read the text on slides displayed on the front panel?
A study conducted in Australia in the late 1990s (the 1999 Kalyuga study) compared the learning outcomes of a group of students who watched an educator’s presentation involving a visual text element and an audio text element (meaning there were words on a screen while the teacher was also talking) with those who only listened to one lesson, minus the pesky PowerPoint slides. The researchers concluded that using visual stimuli involving words while a distinct auditory presentation is provided increases cognitive load, rather than reducing it.
This is called the redundancy effect. Verbal redundancy “results from the simultaneous presentation of the text and the verbatim”, Increasing the risk of overloading working memory capacity and therefore may have a negative effect on learning.
Consider, for example, a science lesson on food chains. A teacher can start by teaching the difference between herbivores and carnivores. At the top is a slide with definitions of each term. The teacher starts reading directly from the slide. Duplicate pieces of information – spoken and written – do not positively reinforce each other; instead, the two students’ abilities to manage information flood.
Researchers including John Sweller and Kimberly Leslie argue that it would be easier for students to learn the differences between herbivores and carnivores by closing their eyes and listening only to the teacher. But students who turn a blind eye during a lecture are likely to be called out for “not paying attention.”
How to lighten the load
So what do you do ? How do you make sure your kids learn from your lectures rather than ending up with brains that look like too wet sponges? (And keep in mind, entrepreneurs, that could also apply to your product presentations.)
Richard mayer, a brain specialist at UC Santa Barbara and author of the book Multimedia learning, suggests the following prescription: Eliminate textual elements from presentations and instead speak through dots, sharing pictures or graphics with students. This video illustrates exactly what he means:
This approach, he suggests, is particularly suitable for subjects where geometric graphics and visual imagery are essential for understanding key concepts, such as food chains, the water cycle, or area calculation.
Other studies, such as a separate Australian survey conducted by Leslie et al. (2012), suggest that mixing visual cues with auditory explanations (in math and science classes, in particular) is essential and effective. In the Leslie study, a group of grade 4 students who knew nothing about magnetism and light learned much more when presented with both pictures and a teacher’s explanation than a separate group that received only an auditory explanation.
Are you a science teacher? Display a picture of a lion’s tooth and a zebra tooth on the screen while explaining the differences between carnivores and herbivores. Teach the humanities? Circle the number “1776” with painted images of the Founding Fathers signing the Declaration of Independence, rather than including clear facts in your presentation.
And if it’s difficult for you to eliminate words entirely from your PowerPoint presentations, especially when you want students to master these key vocabulary words, here are some more tips:
- Limit yourself to one word per slide. If you are defining words, try to set up the vocabulary word and an associated set of pictures, then challenge students to infer the definition.
- Honor the “principle of customizationWhich basically says that engaging learners by providing conversational content will increase learning. For example, Richard Mayer suggests using a lot of “I” and “you” in your text, as students generally identify better with more informal language.
Do you have a favorite theory practice that works for your students? Leave your comments below, I’m all ears. And the eyes.