Tension

I have recently noticed that three of my favorite films ( two which have been watched in AOF) involve tension building. Elephant and Rosemary's Baby both start out as calm albeit odd. The audience knows something is not right and begin to ask themselves questions. Why are Rosemary's neighbors' so friendly? Why are two boys dressed in Camo entering the school? Why does the camera linger on things that appear to be insignificant?
Elephant centers on a typical school day that will end in horrific violence. In Elephant, Gus Van Sant deliberately films insignificant situations throughout the day. For example: people walking down hallways, rolling film or having trivial conversations. However cracks begin to show as the ordinary changes into the perverse. Two cafeteria workers go into the kitchen to smoke a joint, three chatty girls go to the bathroom to vomit in perfect unison, and a boy walks through the cafeteria nonchalantly taking notes.
Gus Van Sant even makes the eruption of tension visual on screen. Gus Van Sant deliberately films the school as colorless throughout the film. However at the end of the film when the school is inevitably set ablaze the school goes from gray ( the most calm of all colors) to red ( the most intense). This is what the day has been building up to: a literal explosion of pent up tension contained inthe school.