Russian Americans.

My roommate and I meet 2 guys who originaly Russian but were born in US. They have both russian parents and always speak russian with them. We talk with them in Russian but they respond us in English because it is much easier for them)) I was very surprized that they couldn't read and wright in Russian.We had so much fun to talk with them.They said that is very good practice for them to speak with us but sometimes when they try to tell us something in russian we don't understand.