Welcome Patrick.
- an RSS feed could work if you want to be fancy.
- use a FirebaseDB or CloudDB to post text on the devices of everyone who has your app. You could be the only person to update the app but all users could read the 'news' you supply and keep updated.
- Use Google Sheets to provide your news app with new content .
Have you considered RSS news feeds. This is a link showing [how to create your own rss feed It might be helpful although it discusses non App Inventor technology an App Inventor app might link to.
================================================
These are some existing commercial RSS feeds:
=================
These are ways to access RSS feeds using App Inventor: These are ways to access RSS feeds using App Inventor:
This contains some info about creating an RSS news reader
Be aware, some of the information might be dated.
===================================
A more modern example show what an App Inventor app could capture from an RSS feed:
What you depends on your resources. I think a CloudDB or Google sheet type app would work best for you. 
Especially for school specific information and exams. It would be easiest to code.
Something similar (school lunch program using csv)