Ok, I worked out the workflow to focus a class to specific website based on the material in the video. What I did not know was you can scope a configuration file ( the web content filter ) based upon a smart group. That smart group was based on having a config file "App Lock" and being a member of a particular casper focus class. The "App Lock" config file is installed on the student iPad when focused.
I'm a bit concerned about possible conflicts when a device is a member of multiple classes.
Anyway, hope this helps someone.
