<p>so i don't understand...after you ask a teacher for a recommendation letter,do they immediately mail after they're done...or do they give it back for you to mail...i ask this because how would you know if they did a good job in writing the letter in order to determine whether you really want the colleges you're applying to read it</p>
<p>If you give them an addressed, stamped envelope, they'll mail it. Otherwise, they'll give it back to you - some will give you the letter plain, most will put it in a sealed envelope. Don't count on being able to see your recommendation once it's been written.</p>
<p>Generally, teachers have a lot of recs to write, and that extra work adds up quickly. So they probably won't agree to write you a rec unless they believe you deserve the effort. As a corollary, if someone asks a teacher to write a rec and then decide not to use it once it's written, they've just wasted a lot of the teacher's time. So pick teachers that you trust and know well, and ask them, "Do you think you'd be able to write me a positive recommendation?"</p>