Answer:
The children sailed paper boats before dinner.
Mothers call the children inside when dinner is ready.
She fell while she was playing and injured her knee.
Explanation:
Prepositional phrases are composed at least of a preposition and an object.
The word 'when' used as a conjunction means 'at the time that', and is followed by a subordinate clause.
The word 'while' is used to connect two events occurring at the same time, and is followed by a subordinate clause.
Based on the excerpt of the student's speech, it can be said that the rhetorical device being used is "Ethos". The excerpt is trying to make an appeal to ethics. The speaker is trying to establish his credibility by making enumeration of what he has done and what he can do.He is trying to convince the audience of his character and his capability.