In the beginning of the chapter,Lennie and George are by the river and Lennie put his head in the river
Lennie was messing around with the puppy and he accidentally kills the puppy and is mad because then he won't be able to tend the rabbits.
Lennie is in the barn with the dead puppy thinking about the consequences when Curley's wife walked in and lennie got his hands stuck in her hair and she freaked out so he shook her and he broke her neck and killed her.
Literary Device: Foreshadowing
Lennie was hiding after he killed curley's wife. He started hallucinating about things while hiding
Lennie was with George and as they were talking George killed lennie and went on with his life because he had to do what he had to do.
This is foreshadowing by showing how Lennie once killed a girl before so it shows that he's gonna end up killing someone else later on in the book.