OK, the big thing about "The Big Sleep" (TBS) is "Film Noir" (FN). FN is the idea of using the constrast of black and white to portray ideas or emotions in a film. In TBS FN is used to portray good and evil, with the good characters often in good light, and evil cahracters or acts in bad light. Light is also used to obscure or reveal clues and identies of criminals.
Another techniques is "signposting". TBS contains several shots of "signs", the door to the house, street and shop signs, as well as the sign to Marlowe's office. These are used to help the viewer locate themselves within the plotline, and serve as good ways to break the scenes.
Context is easy. Talk about the time period, and what the means about the type of places the characters go to, the type of crime invloved and the issues that are and aren't disscussed.
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