“A Lexical Chunk is a unit of language which is made up of two or more words.
Here are a few examples of lexical chunks :
Good morning.
Nice to see you!
What’s the time?
Other lexical chunks can include phrasal verbs, idioms, collocations and so on.
Lexical chunks are the common coinage of English. They’re the bread and butter, the everyday and the mundane. They’re the reliable standards around which we can hang poetic and emotive language.
Changing Chunks
Some lexical chunks never change:
I’m fine thank you.
Enough already!
But others can have various parts substituted:
Where is the …
Pass the …
Teaching Lexical Chunks
The key to teaching lexical chunks is to treat them in the same way as individual words. So, for example, instead of having flashcards with a single word on them, have flashcards with the lexical chunk in its entirety.
Like single words, of course, they should also be taught in context. Take these typical conversations which native speakers have all the time:
A: Hi, how’s things?
B: Not bad, thanks. How are you?
A: Good.
A: Good morning.
B: Good morning.
A: I’d like a cup of coffee, please.
B: Sure
And so on. Rather than over thinking them and breaking them down into individual words, teach them as a whole and have the class practice and use them. Then, when the time comes, they can repeat them almost verbatim without thinking which is what native speakers do.”
Vocabulary in Chunks 
Thanks for the repost.