Learning is a complex set of processes that may vary according to the developmental level of the learner, the nature of the task, and the context in which the learning is to occur.As already indicated,no one theory can capture all the variables involved in learning.

References: Gredler, M. E. (2001).Learning and instruction: Theory into practice(4th Ed.). Upper Saddle, NJ: Prentice-Hall.

A learning theory, there, comprises a set of constructs linking observed changes in performance with what is thought to bring about those changes.

References: Driscoll, M. P. (2000).Psychology of learning for instruction(2nd Ed.). Needham Heights, MA: Allyn & Bacon.

A learning theory is made up of a set of constructs linking observed changes in performance with whatever is thought to bring about those changes. Therefore since "learning is a complex set of processes that may vary according to the developmental level of the learner, the nature of the task, and the context in which the learning is to occur," it is apparent that no one theory can capture all the variables involved in learning (Driscoll, 2000, p.10).

References: Driscoll, M. P. (2000).Psychology of learning for instruction(2nd Ed.). Needham Heights, MA: Allyn & Bacon.