Creating groups for taking a quiz

[rdclark]

I want to have three versions of the same exam (e.g. Mid Term 1).  I want to divide the 33 students into 3 groups of 11.  These 3 versions will vary (quantitative problems).

I tried creating one group, but I can't find a way to put the other students into two more groups.  How can I create 3 groups?