The dialogues can be quite simple as follows:
Immigration officer: - Good morning/Good evening. Your passport please.
Traveler: - Here you are
Immigration officer: - Where are you traveling?
Traveler: - I am going to Calcutta, India.
Immigration officer: Wow! You are traveling far! You would be taking about three planes to arrive there.
Traveler: - I believe so, yes.
Immigration officer: - What is the purpose of your visit?
Traveler: - I will be attending a conference for journalists.
Immigration officer: -That’s great (officer stamps passport). Here is your passport. You have a great trip.
Traveler: - Thank you Sir/Madam.
If there are not many students in the class, and the student has chosen a far destination like India, he or she can pretend to pass through other immigration controls before arriving.