Scientists begin the research process by writing a question they would like to answer. The question must refer to something that can be studied using scientifically designed experiments; it must also be written in an open-ended manner. For example, a question about why birds fly south in the winter is better crafted than one asking whether birds really feel warmer when they fly south or whether they have some kind of ESP that tells them where the warm areas are. After crafting the question, scientists then read studies about the subject. They learn what other scientists have studied and discovered so that they can avoid repeating work and can generate ideas about the answer to their question. Scientists then come up with a hypothesis or possible answer to their question. The hypothesis must be falsifiable. Falsifiability means that evidence can be collected that proves the hypothesis is not true.