Critical thinking

On the topic of critical thinking, I suppose I really don't do nearly as much with encouraging critical thinking as I should in my classroom. I suppose teaching a first and second year language course, I imply focus on the more verbal skills that is simply memorization and application of concepts rather than much with critical thinking. There are occasionally "categorizing" and higher level thinking skills like trying to group items into categories and figuring out what doesn't belong in the category, but other than those sorts of activities, I suppose there's not very much critical thinking. I think they are very important for students, and I guess I just think my subject matter doesn't lend itself to critical thinking as other subjects do. I'm sure that's probably false and I could do as much with it as any other subject could, but I can't think offhand of many ways to make it more critical-thinking based. Maybe I should have some peer revisions of written language paragraphs, which I do use on occasion, but I'm sure I could do more and I just don't. Any suggestions would be welcomed!