When I started teaching at universities in the second half of the 1980s, I never used slides and only rarely it would have been possible. Sometimes in Finland I was asked whether I needed an overhead projector, and I never did. Estonia was not the e-country back then. Even when I became professor in Helsinki, a marker, a whiteboard and the human voice were quite enough for me for some time. And when I started to use slides I discovered this opens up a lot of possibilities, but takes away a large number of them as well. Knowledge is becoming increasingly fragmented: in a good slideshow, the visual background has to change quickly so that the audience would not become bored with the never-changing picture. Which is why you can never elaborate and never stray off the planned course. This is truly a great pity, because lectures are a good way of teaching only if their content is not predictable, only if they are indeed "happening" on the spot as a joint effort. Still, good slideshows are a value in itself. Visual should be visual. The last thing to do is to write down the main things you have to say, project them on the screen and then carefully read them out. Slides should contain images, not just images related to the subject, but images that metaphorically help to make the point - and to remember it, for those who listen.
On the whole, though, I believe that classroom time should be reserved to interaction. Which is why I increasingly teach in the seminar form, assigning lists of literature for students to read and commenting on their impressions, thoughts and opinions. I also normally admit students from various cohorts to the same seminar, where I try to assess them on the basis of their achieved ability. Usually the younger ones listen, the intermediate ones sometimes interrupt and ask questions, while the older ones, the graduate students among them, have already quite solid opinions on the matters discussed. So the torch is passed. Knowledge is born in dialogue.
