Hello,
A few days ago at school, I wanted my students to sign in and most received a message saying they had to wait 900 seconds.
Any thoughts on that?
Thank you.
Bernard
No problem keep calm my friend
Hi! We have throttling enabled on the registration page as we’ve had issues with spammers creating multiple accounts in rapid succession. Likely you were using the computer lab, so all of your students would have been accessing the registration page from the same IP address. We’ll see if we can do anything to help fix this for teachers who want to put their students on the site!
Funny message though alex, you must admit. Trying to teach those students division?
Certainly not the intended audience 
We’ll be adjusting this soon and after the change it should no longer be an issue in cases like this!