I like your idea - but have not yet looked inside yet!
Your idea is to create an extension for a Modul where a teacher can create an unique evalataion for that task in that modul?..
I read now your explanation...
If you look to the optional gradebook of Gustav several things are already solved there in a broader way:
- You can bring in a calculated column with very flexible rules like: "take the first ten marks, drop the lowest and place the average of the rest in the calculated result column.
- Grades now already offers more choices then 1,2,3,4.5 and pass,fail
- I think that it makes more logic to do the weighting only on the place where you have the overview of all the assignments: the gradebook.
- Do you want to bring in bonusses? make a column for it..
- If I show during presentations this grdaebook, the audiance adores me for that, so I hope that development power of Moodle.com will go to this gradebook first..
All this said, I still like your idea. Especially teachers who want to drop the cold system of number-grading, need a place to show how rich they are looking to their students, how they use sets of scales to grade open assignements (rubrics?), and then...
...then you must visualize on that page how they must express their final ordial in a summarizing (cold) number on the bottom of that page that goes to the gradebook..
Users need a view-right for this ordial page to figure out how that number was constructed...
If it is possible to hang this ordial page in all the tasks moduls (Workshopwill need a special treatment), you would add a great new option to the Moodle Spirit (Ask Ray Man for help?)