The number of kids in your class who prefer apples to oranges, how a stain responds to a cleaner and the inches a tomato plant grew when watered with lemonade are all examples of data. Facts, observations or statistics assembled for analysis represent data. In a science fair, data is the answer to the question you asked when you made a hypothesis. If you are unclear about the methods for the science fair, ask your teacher for help.

Data is usually divided into two categories -- quantitative and qualitative. Numeric information which is measured with tools such as a ruler or graduated cylinder is quantitative data. For example, you might measure the amount of rainfall over a month or determine how much a plant grew when kept in a dark room. Qualitative data involves the look, taste, smell, texture or sound of something described with words. When you observe that ketchup leaves a darker stain than mustard does on a white shirt, you are collecting qualitative data.