Interview for administration job at Uni of Oxford, what's the work related exercise?

I have an interview for an administration job (band 5) at the University of Oxford.

This is the information I received about the interview:

"The interview will be comprised of competency-based questions, therefore please come prepared with examples of how you can demonstrate your competence against the job description and selection criteria.

Your interview will last approximately 45 minutes.

There will be a 20 -minute work related exercise to undertake before the interview. No preparation is required."

Has anyone has a simailar interview with them/has any idea of what the work related exercise may be?

My guess is Excel, however I want to be as prepared as possible.

Thanks!