I remember these from my school days, and how in awe we all were about the GUI. Having sneaky games of Lander when the teacher wasn't looking. Using the art program to draw the usual cock-and-balls, etc.
I found a great bug in the operating system that you could use to bork your classmate's floppy disks. You could drag and drop a parent directory into it's child, and then it would recursively copy until the disk filled up. For some reason, it wsn't possible to simply delete the directories, so your only recourse was to reformat the disk.