(This posting includes a handout which you are welcome to use with your students.)
One of the most common grammar questions I’ve been asked by students or tutors whom I’ve trained or new teachers whom I’ve mentored concerns sentences like:
“While eating our dinner, we enjoyed the sunset.” [Subordinator (While) + Verb-ing (eating).]
Question: Grammatically speaking, what is “eating”?
It’s called a reduced form. The writer is reducing an adverb clause to a phrase.
Original sentence: While we were eating our dinner, we enjoyed the sunset.
Reduced form: While eating our dinner, we enjoyed the sunset.
We can use these with subordinators like before, after, while and since.
This phrase can come at the beginning of a sentence as in the example above and in the title of this post or in the middle of a sentence:
She bumped into a chair while she was looking at her smartphone.
She bumped into a chair while looking at her smartphone.