Dear Alison Johnson,
Good day!!
Apologies for the inconvenience caused and please don’t worry, let’s work together on your concern and move towards a resolution path.
I understand your concern and I would like to convey that I have tested the behavior at my end in my educational test tenants, where the teachers are able to setup the Class Notebook in the Class Team in the Microsoft Teams without any issue.
Since you mentioned the problem happen with the Microsoft Teams in the browser or application and same issue with the different teachers, I have checked the service health dashboard at the Microsoft end where there is no related incident found.
In this situation, I believe there should be some backend issue at your tenant and I am sorry to convey that the problem should be further investigated by the related development team, where they can collect the HAR logs while reproducing the problem and perform further investigation.
So, I request you to connect with your IT admin of your organization (How do I find my Microsoft 365 admin? - Microsoft Support) and raise a new service request from the Microsoft 365 admin center so that the related development team will connect with you and investigate the issue further.
Reference: Get support - Microsoft 365 admin | Microsoft Learn
Note: We apologize for redirecting you to related development support team because the moderators in this community are limited with the resource for further investigation and to get a quick resolution to your problem, we requested it.
Appreciate your patience and understanding. Have a great day!!
Best Regards,
Sophia