Since you say your audience is already familiar with Photoshop and Illustrator, I would prepare both a multi-layer PSD file and a multi-layer AI file and bring them into After Effects as comps (not as “flattened” files) to show your audience that After Effects basically adds “time manipulation” to Photoshop and Illustrator. Show them how you can have discreet control over each layer (as set up and saved in the source applications) and how you can add keyframes in the AE timeline to the various properties like position, rotation, scale, and opacity. Explain how applying “effects” to layers is similar to applying “filters” in Photoshop. I would show them that you can work with everything in 2D if you think of a composition as a multi-plane camera and your layers as a “stack” of “cells” (old, traditional animation terminology), but I would also touch on the concept of manipulating layers in 3D space and using virtual lights and cameras. I think it would be worthwhile to bring in vector art from Illustrator and turn on the “continuously rasterize” button in AE to show the audience how you can maintain razor-sharp graphic edges when animating scale up (or “zooming in”) on a graphic element since this is very different from zooming in on a raster graphics image that quickly breaks down as it becomes pixelated. As part of the same presentation, but as a different portion, I would show an example of working with video footage and applying effects to that as well as touching on the integration of CG elements with video footage (compositing, match-moving / 3D tracking, etc.). Seems like more than enough stuff to fill an hour without throwing too much stuff at a group of newbies.