Moodle 2.8 and 2.9 gradebook advisory follow-up

In late May CLAMP became aware of several critical bugs in the Moodle gradebook which were introduced in 2.8. After assessing, CLAMP issued an advisory recommending against upgrading to Moodle 2.8 or 2.9 until those bugs were mitigated. Since then Moodle core and members of the Moodle community have made considerable progress working on these issues, and CLAMP believes it is now safe to upgrade to 2.8 and 2.9. Please continue reading for a full explanation.


Moodle 2.8 included significant changes to the gradebook. These included, in part:

  • A revamped interface for the grader and user reports with improved scrolling and display on all devices.
  • A new “natural weighting” aggregation method.

On the whole these are positive changes. CLAMP evaluated the new gradebook at the 2015 Winter Hack/Doc at Occidental College and the participants there thought it much improved on the old gradebook.

It was always expected that certain edge cases such as drop low/keep high and the sum of grades aggregation method would lead to minor variations in calculated grades. This assumption was incorrect. One major institution reported that after upgrading to 2.8 11% of all enrolled students were affected, some in major ways.

For each individual grade Moodle has always stored the maximum points for that item at the time of grading. Thus if a teacher changed the maximum points for an item after issuing grades two students could have different values for maximum points stored. However, this number was not used in calculating a grade: Moodle always presented to teachers and students a grade based on the student’s individual grade and the current maximum grade.

Moodle 2.8 changed this behavior: the individual maximum points are now used to calculate grades. This means that there are now many cases in past courses where student grades appear to change, often dramatically. This has important consequences for grade auditing and will reduce faculty confidence in the gradebook. As initially released, any institution which upgraded from a prior version of Moodle to either 2.8 and 2.9 would have seen these fluctuations.

On clean versions of Moodle 2.8 and going forward on upgraded versions this behavior could have caused confusion as the maximum points for a grade item would no longer be a constant for all students in a course. Furthermore, the grader report would in places show the current maximum points for a student even when that student’s actual maximum points varied from it.


The new stable releases of Moodle, 2.8.7 and 2.9.1, released this week, contain several fixes related to the gradebook. For those of you running the Liberal Arts Edition, updated releases with these fixes will be available on Monday, July 13. The most important of these is a new configuration setting for the “minmax” behavior described above. Per the core documentation there are two available options:

  • Min and max grades as specified in grade item settings
  • Initial min and max grades

After reviewing at the Summer 2015 Hack/Doc Fest at the College of the Holy Cross CLAMP recommends that you select the first of these. This mirrors the behavior in 2.7 and earlier: students will be graded according to the current range. Making this selection will mitigate most of the grade-changing behavior described in the advisory.

If you have already upgraded to 2.8 or 2.9 or installed fresh, you will still be prompted to select an option. If any courses were already impacted by the “minmax” behavior then it will be necessary to fix them. Any affected course will display a notice in the gradebook with an option to restore the recommended behavior. CLAMP is evaluating the possibility of a plugin to change all such affected courses automatically.