For this course I provide Khan Academy videos, and suggest questions in the site's practice sets. I don't grade their activity on the site (although I could using the site's Coach role) but believe that this kind low-stakes practice, with feedback and additional resources if necessary, helps students to develop their understanding of the mathematical concepts involved. While instructors and professors might see graded formative assessments as just formative assessments, students may interpret them as summative assessments, and be discouraged if they perform poorly. And really, I wouldn't want to take a test on a section I've just read. I doubt students want to do the same.
For all online courses I provide weekly introduction videos using screen-capture software, that review the materials, resources, and activities for the week. In the past these have just been videos of the LMS, but this term I'll be including a picture-in-picture of my webcam. I'm hoping that this will further develop my presence in the course, and make me seem more available to students.
Will post weekly updates of the course and how it is progressing.