If an instructor wishes to add a student to a course who is supposed to be enrolled in that course, the instructor MUST work with the Registrar's Office to ensure that student is properly enrolled in the course through Joe'SS. Once the student is enrolled via Joe'SS, they will show up in Canvas the next time that the enrollment data in Canvas is refreshed. This happens every few hours, so be patient if it doesn't happen immediately.
This commonly happens when a student enrolls at Missouri S&T after the start of the semester. It can take several days before a student's S&T account information trickles through all of the different services to which they will need access (email, Joe'SS, Canvas, etc.). In those cases, instructors may need to provide printed access to course materials until the student has access to the course materials in Canvas.
If a student needs to be added to a course simply so they have access to the course materials, then the instructor can submit an IT Help Request to have that student added to the course as an Observer. Observers have limited access to any student data within a course, but can see all of the content. This is fairly common for LEAD facilitators who would like to know what is being taught in a course so that they can help students master the materials.