If you use Clever, you don't need to create classes manually! You can simply sync your classes and students with Clever. After you do so, your imported students will be able to use their Clever login info to log in to Formative as well.
1. From the "Classes" tab or from your "Formatives" tab, click on the "Add +" button
2. Choose "Roster Sync"
3. Proceed to click "Sync Rosters with Clever"
4. Log into your Clever account:
Your class(es) will appear including all the students currently enrolled in them.
To re-sync the classes, simply follow the same steps above!