[robbak]

There should be a shell-over-ajax projects somewhere. You'll find most of the heavy lifting has been done for you already.
Remember 'write' and 'talk' - two ways for persons to communicate. Nice ways for the mighty sysadmin to praise you for working out how you use 'echo', or express his annoyance over your misuse of 'sudo'.
While I see the point of it being self-contained, the main thing a BSD user needs to learn is where to find his answers - handbook, mailing lists, google, forum searches, etc. Search first, Try second, Search third, try fourth, bug someone else fifth!

Oh, Edit: Don't forget that there are more than two ways to do anything: Try hard not to penalize someone who does something with awk, when you thought of sed. Check out the recent thread on 'renaming files with sed' to see this in action. Your students will probably find better ways to accomplish a task than you did - don't fail them when they do!