Firstly lets tackle understanding foreshadowment as a technique. Foreshadowing essential means to hint or relate an early part of the text to a later event, for example, in Of Mice and Men we learn early on that Lennie likes to pet mice and other small, soft creatures but tends to accidently kill them as he doesn't realise his own strength. We could then look at the later event of the death of Curley's wife and Lennie's puppy and make a link between the two. Perhaps Steinbeck was 'hinting' at what was to come by exposing, from the offset, Lennie's over-loving and unaware nature.