Doh! I just realised that you are most probably asking for the actual ST9 software.
As your school is currently running ST9, your school should be able to provide you with a copy of the ST9 install media.
You can extract the license file from the ST10 Student Edition download and then use this ST10 license file with your ST9 install media.
If you have issues extracting the ST10 license file please send me a PM with your e-mail address and we can attempt to resolve this for you.
Thank you and regards,