When the student-teacher ratio is 27 to 1, it is difficult to reach out to every student during class, assess his or her understanding, and give individual feedback. When students are working independently during class, I make it my routine to visit every student and have an individual conversation; however, this doesn't happen every day, and there isn't generally enough class time to make it to every student and have a substantial conversation.
Thus, one of the most important tools for me is written feedback. When students turn in work, I assess them for misunderstandings. If a particular misunderstanding is common, I make sure to address it in class; however, many misunderstandings are rather unique, and in those cases I write directly on the paper. Although this is time-consuming, it is worth it because it builds more personal connections to shyer students, and it ensures that each student has written records of what concepts they need to work out. Almost as important is the act of writing positive comments, to congratulate and reinforce the students' efforts.