Providing a consistant look and feel for each module is helpful for the students. They get used to ow you structure your class and can then focuso on the earning objectives. You should also use many of the best practices in online learning... communication, timely feedback, friendly environment, kudos, course announcements , using discussion boards and crerate ne for course questions. You should use different teaching techniques and try different tools, but make sure you achieve the learning objective. explaining "why" we assign some assignments helps the studnts buy in and learn the assignment better , in my experience.
