Reference Letter

I did that for my physiology class because the course was about 500 students, the teacher could not get to know any student on a personal level, so he offered to setup an interview to get to know me better.
However, I think if you are getting an A in a course (preferrable science) you should ask anyways. Some teacher prefer to know you a little better, but if you were lets say top 5% of their class it is usually not much of a problem.

Better to try and not get one, than not to try at all right?

 

The way I got my letters was by taking a lot of science lab courses and going to professors' office hours. I don't know about your college but at my college the lab classes usually have a very small number of students not like lecture classes (300+ students) so the professors have a chance to really get to know you, especially your interests and aptitude. If your college lab courses are taught by TAs, then I would suggest taking advantage of office hours or ask lots of questions during or after class. Stand out from the rest.