The fact is material whose content consists of a  number of facts or information that truth can not be a doubt for debate. For example the fact that the water flowing from the highlands to the lowlands, and so forth.
2. Concept
The concept is a field of study material that the contents of ideas, ideas, opinions, theories or proposition. Abstract concept, but it will be real if it is realized in the form of objects or actions. For example, the concept of an odd integer and represented in figures 3, 5, 7, 9, and so on.
3. Principle
The principle is the practical demands for the implementation of specific actions such as in learning and teaching. Material field of study is the principle ingredient that gives the foundation for the realization of a pebuatan expected that any action taken can be well controlled. Examples of principles of learning and teaching.
4. Skills
Skills consist of skills - skills that should be mastered, particularly those involving motor skills, such as typing skills, organize space, hit the ball, and run fast. Material field of study skills is widely available in the field of vocational studies. How to learn in general with tasks and exercises.