To assign a group of students to a new class follow these steps:
Click your name then click School.
Use the Grade and Class filters to narrow your list of students to the group you would like to assign to a new class.
If the students you need to assign to a new class are currently not in the same grade or class then you would not use the filters. You would manually locate the student accounts and select them.
Use the Select All check box at the top of the left column to select all of the students in the list.
Click the Assign to Class button in the left column.
Select the new class for the selected students.
The selected students have now been assigned to their new class.