Are idioms and slangs part of "Expression"?

[Rosalisa]

Hi teachers,

Are idioms and slangs part of "Expression"? :D
_________________
If you want to change the world, be one of the change.

[Mister Micawber]

.
I would say so. All three terms a loose, though: one man's idiom is another man's slang.
.
_________________
Native English teacher at Mister Micawber's