The students in the classroom next to mine are always learning American idioms. This makes my students jealous, I think, because I rarely teach them idioms. I used to teach them all the time. I have lots of units on idioms, some of which we use today, but many of which left the corpus of American speech a full generation ago. That’s one reason I don’t teach them any more. I don’t want to be responsible for dozens of immigrants saying things like, “Today is a red-letter day,” or, “Good bulgogi is as scarce as hen’s teeth in the U.S.”
The other main reason I hate teaching idioms and slang is because a lot of times, they are so generational and/or subcultural. It just doesn’t sound right when a 60 year old says that something is “dope,” or when a 19 year old guy exclaims, “heavens to Betsy!” My job is to help them assimilate, not get them beat up.
But by golly, they just love learning those idioms. It’s fascinating – dare I say, seductive even. Learning an idiom in another language opens up a whole new window through which to view and understand the culture, and there are SO MANY of them, it’s ridiculous. I mean, idioms ARE English. If you don’t know them, you don’t know squat. Unfortunately, they’re like the secret English that only native speakers and a few lucky learners are privy to. Others might learn them intellectually, but they may never be able to use them in a way that sounds natural. Not all of them anyway.
Here is exactly what happens when you teach an ESL class a list of idioms and new vocabulary, and then have them make up skits to practice using them.