In my experience, we should not assume that English language learners will acquire socially appropriate
The need for teaching socially and culturally appropriate language in social situations is evident every day in our classes. We have all had students who use the same language when speaking to a teacher that they would use when talking to a peer. I once had a beginning English language learners who had learned how to say "yeah, yeah, yeah" to friends during recess. He couldn't say or understand much else in English. Whenever I gave him directions, he would reply, "Yeah, yeah, yeah." I had a difficult time making him comprehend that this was inappropriate language for a child to use to an adult. I finally taught him to say, "Yes, Mrs. Haynes" but I needed to have a translator explain why "yeah, yeah, yeah" was unsuitable for the classroom.
The same thing occurs when a second language speaker swears in class. An English language learners in my school used an "x-rated" expression in his third grade classroom. The teacher was understandably distressed and required that the student write an apology for homework. Even more upsetting to the teacher was that the student's parents did not take the infraction of school rules seriously. I explained to her that swearing does not have the same "shock" value in a person's second language as it does in their first. So the parents were not "shocked" by their child's use of this language. What is considered "shocking" or inappropriate language for the classroom must sometimes be directly taught.
Use role playing to demonstrate social English
I spend a lot of time teaching students how to give and receive compliments, to thank someone for something, to answer the telephone, to ask directions, and to make small talk. Role playing, teacher modeling, peer modeling, and video are all good tools for teaching these social skills. Have students learn how to observe their peers for models of correct behavior. Use real incidents that come up in your class. Have students practice saying "good morning" and "good-by" to their teachers and classmates right from the beginning. Encourage classroom teachers to set expectations for these behaviors. Classroom and subject area teachers need to learn about some of the cultural differences in manners and behavior. You don't want teachers to over-react when a student won't make eye contact or relates to other children by touching them all the time, or smiles at inappropriate times.