How to wipe all content from an iPad to prepare it for another user.
1. Open the Settings app.
2. Tap "General" and then scroll to the bottom. Tap "Reset."
3. Tap "Erase All Content And Settings."
4. Teachers and secondary students only, enter your iPad passcode. Elementary students will not see this prompt.
5. Tap the "Erase" button. You may see one last confirmation/warning. If so, confirm that you want to continue.
6. The iPad will reboot and you will see a white progress bar as the iPad is wiped. You will eventually be taken to the "Hello..." screen. Done!