Let's get this straight. We are talking about Facebook Friends (I call them FF's in class) and a Facebook friend has access to everything you put on your wall (unless you "list" them - more on that later.) It means that if you "friend" someone who hates you that they will be crawling your page and your life looking for something bad about you. It also means that if you "friend" your students and you skip school one day and post "I took a sick day to go to the mall." that you've just ratted yourself out -- in writing. Everyone will know, that sort of word travels fast.