The OP mentioned that images would be displayed in a workshop. My question was how will the images be displayed? He mentioned online.
Web browsers IE 9, Google Chrome 18, Firefox 15 (with a plug-in) and Safari 5.1 are color managed. From my research, I found the following. This part is copied from elsewhere. If you send an image to a monitor without adapting the colors to the monitor's color space, you will get the wrong colors. "Color aware" applications are ones that do that adaptation: • they figure out the image color space. • they figure out the monitor color space. • they map RGB values from one to the other.
So color-aware applications will show the correct colors whatever the color space of the image and whatever the color space of the monitor (provided the monitor is calibrated/profiled).
If that statement is accurate, he can shoot Adobe RGB for the class and not encounter color accuracy problems if the class is using the latest browsers (or other color managed program) with a color calibrated monitor.