There are several open substitutions that have to be dealt with owing to the absence of teacher Hugo on Monday
The changes to the regularly scheduled lessons are displayed in the timetable.
All changes to the current timetable are displayed in red. You can see that the first two periods of the timetable of class 3b have to be covered because of the absence of teacher Hugo. Hugo's absence is highlighted in his timetable, as well.
The changes to all periods involved are displayed as a list in the substitution window (right mouse click / Substitutions), in this example four periods.
There are two changes in the first period compared to the regular timetable:
An open substitution is marked with three red question marks ???. This open substitution must be filled with a suitable substitute teacher.