Types of Science
Science classification can be based on the method knowledge is presented.
This is found in books on linguistics, mathematics, logic, or the theoretical part any subject has: the logic connecting it and subsequent rules to apply in practice. Knowing the ABC's of speaking, counting and thinking saves much time learning. Any science has its own terminology, laws and theories, that speed up its understanding and protect learners from getting lost in details of the realm of such science. Abstracts present no new knowledge; yet they cement all aspects of knowledge together. They are vital tools of learning: a medium, not an aim.
This is what most science curricula books are about. It's where one can find the gist of scientific research and achievements made by scientists over the ages to improve our life quality. The study time devoted to a basic science should increase over time as one becomes more interested/specialized in it. One should at least be an expert in one field of knowledge, while having basic knowledge of the others, since no science exists in a vacuum away from other sciences.
The most prominent type of applied science is SELF-HELP. Unlike abstract sciences, practical self-help books focus on the goal of learning. They are a shortcut to solve, rather than analyze, problems with. A professional needs them too, to not lose the directions or become too theoretical about knowledge, forgetting his/her main objective. Scientists don't live in ivory towers; they keep searching for solutions to our everyday problems. Learning about science applications narrows the gap between what we learn and need.
Science comes first. Natural sciences have a "ripple effect" on all other sciences, faster than any other field of knowledge, being triggered by a new scientific discovery, invention, or even development and application of a known concept, rule, or law. Thanks to technology, scientific knowledge is accelerating, while replacing, sharing, or supporting the other less concrete sciences (theoretical, social, artistic, psychological, or philosophical) largely dependent on reasoning and deduction, until the advent of scientific data and methods revolutionizing them. Our future problems will be mostly scientific, rather than political, social or psychological.
Whatever the field of knowledge one loves, it must be derived from facts and processed by sound logic, with natural sciences and mathematics helping each, respectively.
It is useful to learn how knowledge is developing: to understand the present trends of knowledge and predict future ones (needed for future studies and long-term plans). It includes SCIENCE PERIODICALS, FUTURE STUDIES, HISTORY OF SCIENCE BOOKS, etc.
History of science books may include old textbooks, even those taught centuries ago. They should be read along with "history books" and vice versa, to understand the context the latter were written in and the mindset people had then, however primitive the knowledge they had sounds to us now. It is not surprising that many old textbooks contain scientific errors, backward methods, childish enthusiasm about common topics, and disinterest in vital knowledge we now have. This should teach us never to take "our" present for granted either, but rather constantly think differently, asking ourselves: What will future generations think of us? What facts do we have now could be wrong? What routes did we forget to take and possibilities to consider?!
Science fiction deals with scientific facts, applications and development in a more liberal literary form, exploring the endless possibilities science can lead to, in future, past or present settings. Science fiction boosts learning motivation, rather than merely presents data or arguments for. It "visualizes" scenarios, examples and contexts where a certain scientific fact/possibility is applied. Simulating reality or visualizing alternative realities by fiction forces us to take science seriously and personally, to solve the problems each of us might face if such fiction became a reality we must live with.
* * *
Science classification can also be based on content. There are distinct scientific differences, similarities, and "overlaps": geopolitics, sociolinguistics, science history, animal psychology, sport (medicine+physics), dance (medicine+geometry+motion/sound physics), food (medicine+chemistry+anthropology), etc.