What types of bias could be in a survey asking students how many classes they take per semester?

Thanks
-MC

How do most students count classes? Do they count labs as classes? Or is a lab counted as connected to a particular class?

Would the survey consider only classes taken during the standard fall and spring semesters?

How would a student count classes taken during between-semester times (e.g., winter break online classes or summer classes)?

What else can you think of?