What is "Student Progress" percentage bar for?

The Student Progress percentage bar on the assignments page indicates how far along your class in on the assignment. This show the percentage of completed questions. A completed question is a question that a student has either gotten full-credit or has run out of attempts and can no longer work on it.

For example, if your assignment has 10 questions and your class has 5 students in it, then there are 50 total questions to be answered. If student #1 answers all 10 questions correctly, then you now have a 20% completion of the assignment. If Student #2 gets 5 questions correct, 3 questions partially correct but runs out of attempts, and 2 questions partially correct but still has more attempts, then student #2 has completed 8 questions bringing the total assignment completion percentage from 20% to 56% complete.

This metric can be used to help determine how far along students are, whether or not to extend the deadline, etc.