The 2009 Illusion of the year has been announced! And its a good one - a powerful motion illusion. It works well for me on my screen and I bet it would work well for an entire class if it was projected. My challenge with these perceptual illusions is always relating them to the perception principles in the text (they are often VERY complex) but the description provided for this illusion is pretty clear. The web site also allows viewers to change the parameters of the illusion, etc.
Black Plague: Newscast from the Past
23 hours ago