
Kelly O. answered 03/15/19
College Professor Ready to Help!
A clause doesn't necessarily have to have a subject. The difference between a participle phrase and a participle clause is that a participle phrase functions as an adjective, and a participle clause functions as an adverb, giving information about condition, result, reason or time. A participle clause also has the same subject as the main clause. So in your sentence--
Walking to school, I spotted a car driving erratically toward me.
"Walking to school" describes the conditions under which you noticed the car. It modifies "spotted."
However--
"Soaring above the river, the eagle searched for a fish to eat."
"Soaring above the river" modifies "eagle," so it is functioning as an adjective; therefore, it is a participle phrase.
Hope that helps!