I enjoy teaching the big things (LISP, Xrefs, PS/MS, Standards, etc.) but I also get a kick out of teaching the little things too that often get overlooked or just fall between the cracks. (Poor neglected commands/options!)
Here's a neat little trick if you want to lock in an angle for drawing a line.
Start your line command and pick a start point.
At the Next Point prompt, type in something like "<17", without the quotes of course.
Move your mouse around to the area that would be at 17 degrees (or whatever angle you input) and PRESTO! instant polar angular override!
Cheers,
Robert