Prevent Students from Deleting a Page

Good afternoon,

A teacher contacted me and said that students were accidentally deleting pages while annotating pdf math worksheets. She does not want to lock the document, but wants to prevent students from deleting entire pages by accident.

Is there a way to set the pages as backgrounds so they are not able to be deleted? I apologize if this has been asked & answered before. I looked through the app and was not able to find a solution.

Thank you,