A principle is a relationship between two or more changes, like "water expands when it freezes". There are two major kinds of principles: process and causal.

1. A process principle is a sequence of natural events.
1. Example: "A seed grows into a seedling, which grows into a mature plant, which develops a flower, which produces seeds, and the cycle continues." 
2. Contrasted with procedures: A sequence of natural events is not a sequence of actions performed by a person, which is a procedure rather than a principle. 
3. Kinds: A process principle may be linear (with a beginning and an end) or cyclical (with no beginning or end).
2. A causal principle is a cause-effect relationship between two or more changes.
1. Example: "An increase in the price of a good causes a decrease in the amount demanded and an increase in the amount supplied". 
2. Contrasted with process principles: In process principles you can't say that one change causes the other. 
3. Kinds: Causal principles usually have multiple causes and/or multiple effects.

• What is Principle Using?
• Why is Principle Using Important?
• Principles for Learning Principles
• Principles for Teaching Principles
• Development Procedure for Designing a Principle-Using Lesson
• Skill Builder