Columbia University [Three professors in front of a chalkboard.]
Columbia University [Three professors talking in the front of a classroom.]
Columbia University [Three professors talking in front of a chalkboard.]
Columbia University [Three professors in the front of a classroom.]
Columbia University [Three professors talking.]
Columbia University [Three professors.]
Columbia University [Professors talking in front of a chalkboard.]
Columbia University [Professor talking to a student.]
Columbia University [Professor teaching a class.]
Columbia University [Professor talking with student.]
Columbia University [Students in a professor's office.]
Columbia University [Professor teaching a class in a lecture hall.]
Columbia University [Two men talking in a classroom.]