I must say I disagree strongly with the suggestion that students should underline the "important parts" of their essay answers. Frankly, were I a student faced with this requirement, I'd underline the entire thing, and feel the prof was being insulting. If I didn't think a given bit of information was important, I wouldn't have included it in my essay.
That's not to say it's not ok for profs to skim from time to time -- I do -- but I really don't think that's a message we should be sending to our students.
