Your CRN (Course Reference Number) might be slightly different than your timetable. Large classes are divided into smaller sections for scheduled classes but all students use the same MyCanvas course.
In most cases, the CRN will be only differ by a few numbers. For example:
Course CENG 10034
Timetable: CRN 26593
MyCanvas: CRN 26592
You should attend scheduled classes based on your timetable.