Bit out of the box:
- Add a (sub) category in your gradebook with the scale/points set to what you need
- Add a quiz:
- grade category: the category you've added to your gradebook
- attempts allowed: 1
- shuffle within questions: no
- review options: disable all
- Set the total marks to "1"
- Add one multiple choice question asking them to mark themselves. Add the grades they can choose from to the multiple choice answers and set the "Grade" for each answer to the appropriate percentages, for example:
- Fail - None
- Pass - 33%
- Merit - 67%
- Distinction - 100%
- (Suggestion: go back to your Gradebook setup to hide the quiz from the students.)