Speak the Language of Your Students (or have them speak yours)

My middle-students come to school every fall with the latest, like, slang-of-the-year. ya know?  Like, 'm i bad, like, ya know?

I don't forbid it.  It's what we did when we were young, and what their children will be doing, too.  However, I am an adult and their teacher.  When they speak to me, or any other adult, I insist they use the formal language that they learn in school.

It doesn't take them long to learn to switch gears when their audience changes.  They help each other out and, as a class, become stricter than me.  The point is, the slang-of-the-year does not make them unable to speak as they are taught.  What I insist is that they learn when to use which language and I will help them with that.

The same applies to the written language.  There is a time to write formally, and a time 4 text talk (I haven't mastered that), as this article from Valley News Live talks about.

http://www.valleynewslive.com/story/17246069/does-texting-make-u-dum