Scientists are not just interested in facts but also in explanations. That is, they are not just interested in what the world is like, but also in how it got that way. For example, if you walk into your room and find your homework (which you left stacked neatly on your desk) scattered all over the floor, you may be curious to know why it is there. Simply observing that your homework is on the floor is not yet to think like a scientist. You begin thinking like a scientist when you begin to ask what could have caused your homework to be on the floor. Perhaps your homework was blown off the desk by the wind. Perhaps your cat knocked it off. Perhaps your house has a poltergeist (a ghost that tends to throw things around). Which of these explanations is best? A...