As part of the Science Learning Network, the Scanning Electron Microscope (SEM) Web site explores what an SEM is, how it's used, and what images it can produce. The How It Works section has a self-paced tutorial and an interesting movie describing how it functions as well. The other section for students is the image gallery, which has the Animal, Vegetable, Mineral game. Individual images from a SEM are shown, and users get to guess which of the three substances is shown. It isn't as easy as it sounds, but it is fun.