Officials found a piece of notebook paper "showing a diagram of the Columbine High School cafeteria with two X's next to the pillars, " and a list of how many people were there before and after the first lunch period, the sheriff's department said.

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But from the time I got interested in this over a four- or five-year period, I'd go to lunch or dinner with people and they'd say, 'What are you working on?

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Many people experience a period of reduced alertness in the afternoon, what researchers call the post-lunch dip.

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