Assignment details
In the second step of setting up the assignment, you fill in the options which are specific for the type of assignment you are adding:
Upload a single file
If you are adding the Upload a single file type of assignment, you fill in the following options:
Maximum size
This setting specifies the maximum size of the file which the students can upload as their submission.
Allow resubmitting
By default, students cannot resubmit assignments once the teacher has graded them
If you turn this option on, then students will be allowed to resubmit assignments after they have been graded (for you to re-grade). This may be useful if the teacher wants to encourage students to do better work in an iterative process.
Obviously, this option is not relevant for offline assignments.
Email alerts to teachers
If enabled, then teachers are alerted with a short email whenever students add or update an assignment submission.
Only teachers who are able to grade the particular submission are notified. So, for example, if the course uses separate groups, then teachers restricted to particular groups won't receive any notices about students in other groups.
For offline activities, of course, mail is never sent since students never submit anything.