There are many options listed below. Create a private forum for each student to journal and for you to respond to.
Students do activities offline, then reflect online.
This creates focused sustained journaling and keeps a reflective record for both student and teacher. Encourage students to ask each other for help first in the Discussion area. That way whoever gets it first can answer it and students get a quick response. Use anonymous forums to get feedback about the course and how students are doing. To manage large classes, have students discuss in a private topic and then assign one person in their group to post a summary to public.