As a PhD student you are employed to do work for the department. This work usually takes the form of teaching courses.
When teaching it is important to remember to adjust the course workload to match the number of work hours expected for students based on the ECTS-points of a given course.
For example, if a course is set as 10 ECTS-points, the workload for the students is expected to be 1/6 of the 1640 hours, which is a standard year of full-time studies.
This means that one 10 ECTS course should equal about 270 hours of work for the student. This includes hours of class participation and exam preparation, as well as any independent and group work.
Hours can be adjusted to account for holiday periods, or other special circumstances, but should follow a work week of 37 hours as closely as possible.