A prepositional phrase often gives extra information about what is happening in a sentence. Sometimes the extra information tells when. Look at these examples:
I will pick you up in five minutes.
We have basketball practice after school.
Let’s watch television before bedtime.
I must read this book for one hour.
A prepositional phrase can tell when something happens.
▶Now you try it. Find the prepositional phrase in this sentence that tells when: John walked home after the game. That wasn’t too difficult, was it?