As kindly pointed out by a colleague, The Register has been talking about a new study which has shown why PowerPoint can actually detract from lessons or lectures (link is a PDF).
“Humans just don’t like absorbing information verbally and visually at the same time – one or the other is fine but not both simultaneously.
Researchers at the University of New South Wales in Australia found the brain is limited in the amount of information it can absorb – and presenting the same information in visual and verbal form – like reading from a typical PowerPoint slide – overloads this part of memory and makes absorbing information more difficult…”
I remember when at university the hardship of sitting through several lecturers (who shall remain unnamed) who spent an entire two hour lecture talking through a PowerPoint: no expansion; no commentary. And to add insult to injury (s)he’d give us copies of the PowerPoint as handouts. Needless to say, those lectures were often missed as you could do the same thing in the comfort of your own home with a friend reading for you! ;)
Anyway, I have always tried to avoid PowerPoint lead lessons as I hate the fact that the students seem distracted from what I’m saying. The times that I do use them I use them the way (well at least what I believe) they should – to have images, graphs or key terms that will be of use to them. At the end of the day, it’s what I’m saying that is of more importance than what’s on the bored behind me.
The recent study above does show something though, that as teachers we should really be aware of: not to overwhelm the students with information. If using a PowerPoint put blank slides in where you want to talk; if you need the students to copy something from the slide and you want to talk about what they’re copying then say what you have to say first; and try to use PowerPoint to add to your lessons not take away from it.