Classes
A class is a named group of your own students, and assigning a task to it is a snapshot taken at that moment.
Task templates
A template stores the shape of a task, not its words: applying it to another set builds different content from the same plan.
Start times and deadlines
The student is notified when the task starts, not when you send it, and a deadline cannot be changed afterwards.
Reading task statistics
The percentages are counted over what the student attempted, not over the whole task — read them next to the progress figure.