GradeEvent should support grading of Assignables, not just attempts

[ViktorHaag]

The Grading profile at the moment is very narrow; it only allows for grading of attempts which means it can only track results/scores assigned to users when the system already has knowledge about the "attempts" of the users involved. However, this isn't always the case:

• the Grade may get assigned for items that are assessed entirely outside the sensor application's context (i.e. "grading participation" and others) where the sensor app is merely a gradebook and not an assessment engine
• the Grade may get assigned for items that are assigned but not explicitly assessed mechanically -- it seems silly to force the sensor application to synthesize an "attempt" merely to associate with a result

If we allowed for GradeEvent.object to be an Assignable as well as an Attempt, then this would open the GradeEvent up to more flexible use.

[aheitzmann]

+1 to the idea

In the interest of refining this a bit, I note that there is no Assignable entity type, so perhaps the ask is to allow object to be a DigitalResource or AssignableDigitalResource. However, in that case, there is currently no field that can be used to indicate for which Person the Score was generated - that information is currently only present in the Attempt.

Some options that come to mind:

a) Add an optional fields student: Person and assignable: DigitalResource directly to Score.
b) deprecate the attempt field on Score. Make an AttemptScore subtype with the attempt: Attempt field, and an AssignableScore subtype with the student: Person and assignable: DigitalResource fields.
c) Create a new Entity type like DigitalResourceInteraction with assignee: Person and assignable: DigitalResource fields to represent a relationship between a Person and a DigitalResource that they have interacted with, independent of any Attempt. Make Attempt a subtype of DigitalResourceInteraction. Deprecate the attempt field on Score. Add an interaction: DigitalResourceInteraction field to Score.

My final observation here is that I believe the same issue also exists for the Result entity; there appears to be no way for a sensor to specify an overall Result achieved by a student on a DigitalResource, independent of or as an aggregate of the student's Attempts on that DigitalResource, accounting for settings/policies and overrides. (I leave for another ticket the issue that there is no event in the Caliper spec that generates a Result in the first place.)