Hi Mehernaaz Zahir,
Role play for presentation skills can be done thru asking them to sell anything.
This will give you an idea about their langauge,how well they are able to structure the presentation,how do they use the body langauge and the list is endless.
In my opinion this can be made intresting asking them to pretend being a marketing or sales director of a company.
Please tell me if this works
Cheers!!