By making another teacher user a Joint Administrator you can share the Class/Group. To do this you will need to add them to your class by using the purple Add User button in the action column.
Once that has been successful, select the blue Manage Users button from the action column. Select the appropriate user to press Make Joint Administrator.
The user will receive the same level of access to the class and be able to assign zApps and zApp Books, view results and email students.