An animation in instruction may help understanding. For example, many subjects may be confused about the difference between a draw from an urn with balls with and without replacement. An animation is more like a real life demonstration with urns and balls.
The animation above is made with the program Hype in less than two hours (on a mac), including the time to find or make suitable pictures. Hype is easy to use and very cheap ($30) and animations can be saved in several formats. Outside the lab you may have problems with the different kinds of browsers (some of the examples on the hype-website didn't run on my computer), but in the lab you only have to test it for one kind of browser. The website of Hype is http://tumult.com/hype/. Highly recommended! (for the CREEDers: we bought a license.)