Final answer:
In scientific research, a theory is a substantial explanation that's been tested and confirmed, a concept is a general idea representing something abstract, a construct is an assumed but unobservable ideal object, a variable is an aspect that can change, and a model is a simplified or visual representation of these elements.
Step-by-step explanation:
The terms theory, concept, construct, variable, and model are fundamental to understanding the structure of scientific knowledge and research.
A theory is a well-substantiated explanation of some aspect of the natural world that is acquired through the scientific method and repeatedly tested and confirmed through observation and experimentation. A concept is a general idea or understanding that represents something abstract. Construct refers to an ideal object, where the existence of the object may be assumed, but cannot be directly observed or measured. A variable is anything that can vary or change within an experiment or observation; it can be independent, dependent, or controlled. Lastly, a model is a representation of an object, system, or idea that is used as a plan for constructing something or as a basis for understanding something complex.
These components are closely related; concepts and constructs are often incorporated within theories, variables are used to measure constructs or components of theories, and models can represent theories visually or in a simplified manner to facilitate understanding.