Below are instructions for a workaround to get access to Pearson eText for Schools. The explanation I received from Pearson is:
…The problem is with iOS 9.x and the latest version of the eText for Schools app 1.8.3. Users with this combination will not be able to log in via the eText for schools app on their iPad. There is a work around which I’ve attached to this email. Our development is working as fast as they can to resolve the issue and submit the fix to Apple. Thank you for your continued patience.