UPDATE - 2016.04.26
Now with iOS 9.3.1, go to Settings, Mail, add mail account. The "Google" choice works again!! Much simpler than "other" as below ; )
[ keep the following for awhile; everyone should be updated by next school year ]
Click on the Mail icon (usually at the bottom of the Home screen, unless you moved it)
Instead of adding your account using "Google", choose "Other"
see link below for more information.
Thanks, Mr. Kemp! He says,
"I have added a few students already and it worked like a charm!"