Some students will make an edit to Wikipedia that gets undone by another editor. That's OK! You can view all changes ever made to the article — including your student's work — via the "View history" tab. There's no risk that you'll be unable to view and grade their work (and you'll grade based on what they contributed, not what sticks).

It's likely that your student has met an editor with a different view about the article. This is their chance to see Wikipedia's consensus model in action. Your student should check the article's edit history and Talk page for any note about why their work was removed. They should respond to the note, explaining their contributions, with the understanding that we're all here to make Wikipedia a better resource. Hopefully, your student will work out the problem with the editor and agree on next steps.

If a student's edits are completely deleted — which may happen with new articles that don't meet Wikipedia's standards, as well as any edits that include copyright violations — you should connect with Wiki Education staff, if we haven't already seen the deletion and reached out to the student.