Probably would make most sense as an Echo feature (assuming it's implemented within MediaWiki). Although not sure how you would opt in specific people to that.

Changed the title, as 'their' could encourage WP:OWN.

it could work as echo or bot message to user talk or email
opt in via education sign up or event signup

I agree that especially as an initial testing ground, the education extension students might be a very good test group. I suggest to draft a more thorough plan about:

1: who to notify
2: when to notify
3: how often to notify

So that we can distill the required configuration/settings, to make that so.

Note that I have left some personal ideas on encouragement notifications in T126820: Consider providing a mechanism to prompt users to congratulate other users for reaching milestones, which could have some minor overlap for this type of notification as well..

To propose Wishlist items, please submit them on Meta Wiki in November 2018: https://meta.wikimedia.org/wiki/2018_Community_Wishlist_Survey