(Copied from http://docs.moodle.org/en/Development:Quiz_Usability_portal/Attempted_quiz_enabling )

Reasoning behind this improvement

Severe usability problem:

    * An attempted quiz cannot be edited
    * After opening the quiz, the quiz can lock down at any unpredictable time if a student tries the quiz and there is no undo. The teacher may not know about this beforehand and the quiz may end up in an unfinished state.
    * Some teachers are used to previewing things by switching to student role. If they attempt a quiz in this role, the quiz is locked down without warning and there is no undo. This occured in the usability tests of Development:Usability_testing_in_August_2008/Issues_found#Sort_out_the_different_preview_modes August 2008.

Goals:

    * Always warn the user if the are about to do something that affects the set of choices they can make later (User control and freedom http://www.useit.com/papers/heuristic/heuristic_list.html ), and as the undo here is not obvious, tell the user about it
    * Make the user aware of the choices they have in the quiz edit screens, where their actions' consequences are the most obvious.

See: http://docs.moodle.org/en/Development:Quiz_Usability_portal/Attempted_quiz_enabling