If your school uses:
iCloud Mail (Apple)
use the "Sign in with" buttons.
You can still signing by asking for a pin number to be sent to your email address. This works with any provider (including the providers above).
No password is needed and in theory, it has minimal administration. However, there can be issues with overly aggressive email filter settings.
As with the email verification, the email address is entered. Then the user is taken to a secure sign-in page, outside of the app, where authentication can take place.
The sign in process uses OpenId Connect and happens completely in a separate secure browser. 23Equations never sees passwords or two-factor credentials.
Users must choose the correct provider for their school. Teachers should advise students about which to use. Currently, the app can't tell the user which provider matches their email address, but does give hints to help.
Possibilities in the future include adding other providers and automatically suggesting the correct email address. Please get in touch if you wish to discuss this.
These buttons are also available for the online version of the app app.23equations.com
Both methods require the user to be already added to the school account.