Okay, I’m following. It seems like the template allows for more pages most likely because Webflow created it.
One way to troubleshoot is to start a new site from scratch with that template, and try to add an extra page. If it doesn’t let you add a page, it’s because of the account limits, which is normal.
Your best bet is to reinforce (again) to your students to not delete any pages at all until it’s completed.