I have a moodle server since years, but never used it on an academic environment, so I never checked student grades. I used all tests and lessons as autograding activities with further consequences for students.
Now I've started to use it on my highschool, so I've had to check the grades.
When looking at the gradebook, three students have a 10 of 10 grade in a lesson.
Clicking on students names, you can see their grades are 62.5%, 50% and 46% respectively.
The lessson contains (already graded) essay questions. Does it has something to do?