Lexical chunks include collocations but these usually just involve content words, not grammar.
Example
In this dialogue there are five possible chunks:
- Did you stay long at the party?
- No, I got out of there as soon as they ran out of food.
In the classroom
Focussing on lexical chunks is a useful way to look at language and to extend learners' control of it. For example, learners can spend a little time at the end of a reading comprehension exercise identifying chunks in the text and analysing them, or identifying other contexts they might be found in.
Further links:
https://www.teachingenglish.org.uk/article/lexical-exploitation-texts
https://www.teachingenglish.org.uk/blogs/shelliscfc/teaching-chunks-very-young-learners
https://www.teachingenglish.org.uk/article/exploring-metaphors-classroom