Groups are a way to organise your students into different cohorts and compare their results in the grade book, you will find the list of your groups on the homepage below the list of courses.
New Groups
To create a group, click on ‘New Group’ at the top of your list of groups. Give your new group a name and a start date, you can also add an optional description to the group. Once your group has been created you can use the search fields to add a course and students to your group.
Grade Book
You can use the groups grade book to compare the grades of students in the group, you can look at overall scores and also a breakdown by questions.
Test Scores
The test scores tab shows how all students in the group performed on any exercises in the associated course. You will be able to see their overall scores and it will also be colour coded depending on whether they have passed.
Score by Topic
Scores by topic can be used to view how the group is performing against metadata tags, it can show the overall group scoring as well as compare this against individual students.
Adding Grades
Grade boundaries can be added via the general system section of the admin page. 
After adding a name for a new grade you can use the tickbox if you wish for this to be a passing grade before clicking Add. 