Academe's suppliers

Answer:
Yes, criteria for evaluation and selection of suppliers (clause 8.4.1) is a mandatory document. If you consider graduated students as your school products, we can see your system as

We can ask what products or services the school use as inputs to perform its services. Once I helped a school at implementing its quality management system and I remember that they considered as suppliers:
* Transportation services;
* Canteen services;
* Cleaning services;
* Accommodation services;
* Maintenance services;
…
Perhaps you can find these examples as an inspiration to your case.

The following material will provide you more information:
- List of mandatory documents required by ISO 9001:2015 - https://advisera.com/9001academy/knowledgebase/list-of-mandatory-documents-required-by-iso-90012015/
- Should unive rsities implement ISO 9001? - https://advisera.com/9001academy/blog/2015/04/21/should-universities-implement-iso-9001/
- ISO 9001:2015 Foundations Course - https://advisera.com/training/iso-9001-foundations-course/
- book - ISO Internal Audit: A Plain English Guide - https://advisera.com/books/iso-internal-audit-plain-english-guide/