Aren't you at all curious about other cultures? What foods do they like? What do they do for fun in their native land? Do they play or watch a sport, if so, which ones? How do they observe their holidays? How is their school structured and what things do they study? Are their teachers more or less strict? Are their parents more or less strict? Why did they choose to come to your country? How long have they studied your language? Are they enjoying their stay? Are they homesick? Do they skype their parents, if not, how and when do they communicate with their parents and friends? Do they have siblings? Do they have a dog? Is their grandfather still alive? Ask them some slang words and have them teach you some good curse words. I could go on and on but I'm probably boring you already since you could only think of one thing to ask a foreigner in a foreign land
Religion, life styles, morals, beliefs, marriage, technology, the land, restrictions, dress codes, sex (religious take), heritage, what is different now for them vs what there parents or grandparent went through.
In addition to Sasquatch's most excellent list, for which she should be worshipped, ask about the difficulties faced by first and second generation families when they come to a new countries. The pressures they face should waken compassion where none has been before. Find out the differences and similarities between the melting pot and multiculturalism methods of integrating new people.