Inquiry methods are most often used for two major purposes:
(1) To establish "facts" or recurring regularities in the environment. For example: 'How is chocolate made? in an average household'
(2) To test cause and effect explanations for facts. For example: 'are red snakes more stretchy than yellow snakes
Scientific inquiry includes "quantitative" (numbers) and "qualitative" (observations without numbers) methods. Sometimes we can collect data ourselves directly by doing experiments. This is called Primary Data.
Often it is better to use data that others have collected. This is called Secondary Data.