Oh, you want to track a dialogue back and forth? Journal is a possibility. I don't think you want Workshop, which is much more peer review oriented. I'm thinking there's a form of forum you might use.
See the forum for groups and put student and teacher in a group. You can use one forum for all the groups. I think it's a great deal of manual work to do this, but I may have some suggestions about grouping via CSV upload so you're not doing one-by-one group creations.
Using Force Separate Groups in a course, you can make each group's conversation not visible to the others' (apostrophes appropriately placed; think I got the singular correct as well).