The school needs an education account and students should be able to join meetings hosted through a school account:
> Students under the age of 18 should not go to www.zoom.us to create an account because (i) they should only be joining Zoom meeting sessions as participants (not separate account holders) through the School Subscriber’s account and (ii) minors are not permitted to create an account per Zoom’s Terms of Service. The School Subscriber’s account administrator (e.g., teachers) should securely and confidentially provide meeting information and meeting passwords to the student users to ensure the school can maintain supervision and control over its student users’ meeting experiences. If students have already signed up for individual accounts, Zoom can assist schools in fixing this.
The school should contact their account rep about this. I bet they can fix it quickly.