I've been answering a lot of questions lately on our Oberlin Prospective Student Facebook group regarding letters of recommendation. I invite you to check out the forum thread and read the discussion, but I also decided this would be a great thing to blog about and hopefully clear up some things.
First let me start with the basics for those of you completely new to all this. Oberlin is a Common Application school, and we only take the Common App. Therefore, the recommendation guidelines are the same as those for the Common App: we require two recs from teachers who have taught you in an academic subject (i.e. Math, English, Social Science, Science, or Foreign Language), and we ask students to include with those the Common App's teacher rec form. This is just a two-page form that includes some evaluative info as well as class information for the student. There is a small space on the second page of that form asking for a written recommendation. Feel free to attach a separate letter to the form in place of this; teachers don't have to squeeze their rec into the small space on the form.
Let me expound upon requiring that the recs be from academic subjects. We know that many of you may have had more meaningful experiences with an art, music, business teacher/mentor etc., but we still require at least two recs from someone who has taught you in English, Math, Social Science, Science, or Foreign Language. If you'd like, you may send in supplemental recs from an art teacher or the like, but you still need the basic two. Every year we have a surprising number of applicants who don't follow this rule, and it only slows down the review process.
As stated above, we do accept supplemental recs. If a student feels that there is someone who knows them very well and can give supportive and unique information about them to the admissions committee, then they can add the rec to the application and it will be reviewed as supplemental material. This is not necessary, and you are not set back if you only have the required two recs. Every year we admit plenty of applicants who had no supplemental material with their files. Supplemental material will never be the deciding factor; it will only serve to help us get a better picture of you as a person and student. The standard application materials are quite often more than enough for us to get such a picture of the applicant.
I think that covers what I wanted to say. Just a quick tip in parting: if you haven't already, figure out who you want to write your recs, and give them plenty of time (usually at LEAST two weeks) to write them. Hope this helps!