Natural science covers different types of science and fields that study natural phenomena in the world. This implies natural science tries to predict, and understand events that occur naturally. Due to this, this branch of science includes disciplines such as biology, astronomy, chemistry, physics, and geography. However, in the case of computer science, this is not considered part of natural science, because this discipline focuses on the manipulation of digital information rather than in a phenomenon that occurs in the world. Also, different from biology, astronomy or physics that study nature computer science focuses on technology created by human beings.
In a controlled experiment only one variable is changed at a time, while the others are kept the same/controlled so changes can be observed and a causation can be determined.
