Here's how we use Google Drive to save, retrieve and share documents across a school set of iPads.
Before I continue I must state that we have set up Google Apps for Education, which gives us the function to provide each member of school a Google account, giving them access to Google Drive.
To avoid having pupils log in and out every time they use Google Drive we have set them up in two different ways.
1. One account: initially we set up one account which was signed in on all devices. That meant that each class/ user had access to the same account. Then we set up a folder for each class, which was shared with that class' teacher (see screenshot)
2. Separate class accounts: we then changed this method to set up a Google Drive account per class. All class accounts were simultaneously signed in on the devices, a useful feature of the iPad app.
To avoid pupils accessing the wrong accounts, you can activate a passcode security setting for each account. Give your class their passcode only and, hey presto, your accounts are secure.
Do you use the app differently? If so, let me know!