Can a professor scan an excerpt from a prescribed textbook and publish it in an online classroom?

Yes. A professor may reproduce (e.g. scan or digitize) and communicate an excerpt from a copyrighted work to the public (e.g. publish it in an online classroom) for the purpose of illustration in teaching using electronic means, including distance and cross-border teaching. Such use must take place within a secure electronic environment accessible only to students enrolled in the course, teachers, and other persons involved in the educational process, in particular through authentication procedures. The excerpt may not exceed 15 percent of the entire work, and the work must have been lawfully published prior to use.