Observation from Gibbons (2000) + Alessi (1999)

After reading Gibbons (2000) and Alessi (1999) papers, I have the following observation:

Alessi (1999)'s defintion of simulation is a computer program that has an underlying dynamic model in which learner can interact with the model via Graphic User Interface (GUI) with supports of learning.

Gibbons (2000) provides the bone or the underlying instructional design theory of the model-centered learning. He further advocated the use of instructional augmentation which is essentially support for learning as noted by Alessi.

Alessi (1999) adds flesh to the bone and further elaborates on the by-product of modeling - simulation.