<p>Would like to know if a letter from over a year ago would be looked down upon</p>
<p>it wouldn't necessarily be looked down upon, but it may bring up the "why not a junior year teacher" question. If you are certain that the recommendation from a sophomore year teacher will be very excellent/solid, better than any of your junior year teachers' recs, then it should be okay. The content matters more than the year(s) the teacher taught you.</p>
<p>Quoting Yale's admissions site (so you can see their thinking):</p>
<p>Who should write my teacher recommendations?</p>
<p>It is important that your recommenders be teachers who can write about your recent academic work in rigorous academic subjects. We strongly encourage students to ask 11th and 12th grade teachers to write for them. Given Yale's extremely competitive applicant pool, it is probably a mistake to ask a favorite ninth-grade teacher to write, or to seek out a coach or chorus director as a recommender unless he or she has also taught you recently in an academic course.</p>
<p>Yale does not specify that the recommendations come from teachers of particular subjects. It is a good idea, however, to have the two letters come from teachers of different subjects. Choose teachers who know you well and who can give us a sense of both your academic and personal strengths.</p>