Do you believe we should teach using controlled language or authentic language? Should students hear and read language of the so-called real world, or should language be adapted for instructional purposes?
The language in the materials you use.
I’m in favor of using both controlled language and authentic language. Students benefit from exposure to both, in my opinion. If they only hear controlled language in the classroom, they’ll be overwhelmed or frustrated by the contrast when they turn on the TV, listen to the radio, or overhear conversation in public places. Likewise, if they only read adapted texts, they’ll hesitate before reading a newspaper or purchasing a paperback novel. The confidence they feel in the classroom won’t easily transfer to situations outside their language studies. On the other hand, if students are in need of focused study of the language, controlled language allows a teacher to present structures or features of the language in accessible formats and without the distraction of complex language. Particularly in the case of lower level students, it seems unfair to throw so much unfamiliar vocabulary and grammar at them by using a large amount of authentic language.
Does that mean authentic language should be used only in the upper levels? Certainly not. Notice I had said what was unfair was a large amount of authentic language. I think in the proper doses, authentic language is very beneficial at all levels. Consider the approach used in the videos on the site Real English. The creator, Mike Marzio, takes unrehearsed interviews from people on the street, and the final product is one that is comprehensible to ELLs. Editing of the videos controls not the language itself but the amounts of exposure. You may view Lesson1 in his series, for example, in which over a dozen people answer the question what’s your name? The rate of speech is fast and the greetings are varied, but the video is appropriate for beginners.
The language you speak.
When it comes to the teacher’s language, I’m in favor of controlled language. Jeremy Harmer calls it “rough-tuning” and he draws the comparison between teacher talk and parent talk. “Neither group sets out to get the level of language exactly correct for their audience. They rely, instead, on a general perception of what is being understood by the people listening to them. Their empathy allows them to almost feel whether the level of language they are using is appropriate for the audience they are addressing” (Harmer 3). When we are giving instructions or explanations, it’s especially important for students to have full comprehension, so we must simplify our grammar and vocabulary and adjust our rate of speech.
How much authentic language do you bring into the classroom? How conscious are you of rough-tuning your language? Harmer states that the more experience a teacher has, the less conscious the process of rough-tuning is. Do you agree?
 Harmer, Jeremy. How to Teach English. Longman, 1998.