There are many class activities that can generate critical thinking, such as brainstorming, group presentations, peer editing. When students ask each others how they can organize the presentation, what devices they can use to enhance their presentation, when they go over each others writing assignments, discuss their recommendations for correction- all these give students the opportunities to reason, to question, and to make judgments. The instructor has to make sure though that everybody in the group participates in the planning and in the discussions.