Single-sign-on (SSO) is enabled in Naiku through Google authentication. This means that you can sign in directly into Naiku if you've linked your Naiku and Google ID accounts. For example, if you've linked your Google ID to your Naiku account, you can simply click on the Naiku logo above to sign in to Naiku.
If your school uses Google Apps for Education, then your teachers and students have Google ID accounts. You can link your Naiku and Google ID accounts by signing to Naiku with this button on the Naiku sign in page.
If your Naiku account contains your Google email, and if you are currently logged into your Google account (or if you have already authenticated), then you will automatically be logged into Naiku.
If you don't have an email associated with your Naiku account, then you will be shown this message with a link to login into Naiku and authenticate your accounts. If you log in through this link, your Google ID will be then linked to your Naiku account.
You can also link or unlink your Google ID by logging into Naiku (with your usual username and password) and going to your user profile. Click on your name at the top to get to your Naiku user profile. You will see the two tabs below that will allow you to link or unlink your Google ID from your Naiku account.
After you successfully link your Google ID to your Naiku account, you can then login in by clicking on the "G+ Sign in" button on the Naiku sign in page or a Naiku logo (like the one above that has been linked to a.naiku.net/users/auth/google_oauth2?source_action=sign_in) on your school webpage.