Science uses three types of investigations to understand the natural world: Descriptive, Comparative and Experimental investigations.
The Descriptive investigation is used to describe a natural system when nothing or very little is known about the system. Like observing a new specimen in the microscope and describing it by observing the specimen.
A comparative analysis is used to compare two or more variable in nature by collecting data like observing the different colors of the rocks. It provides the data to show the similarity and dissimilarity of the population.
The Experimental investigation is used where experiments are performed to test and answer the scientific questions. The advantage is that data can be used as evidence for future research.
