Learner Control, Cognitive Load & Instructional Animation

Principle 1:
Total cognitive load is comprised of three elements: germane cognitive load, intrinsic cognitive load, and extraneous cognitive load. The goal of design is to reduce intrinsic and extraneous cognitive load, thereby increasing germane cognitive capacity.
Germane cognitive load is the amount of processing capacity performed by working memory on cognitive task, such as sorting or reorganising information - the more capacity engaged in this type of cognitive load the better. Intrinsic cognitive load is the amount of cognitive effort required to bring all parts of a problem together, and is increased as new material becomes more complex, or a person has to consider several parts of a problem at once. Extraneous cognitive load is the amount of processing resources a person has to devote to a problem as a result of elements outside of the problem itself, such as background music.

Principle 2:
When using animation as a teaching tool, learners should be given control over pacing to effect better learning outcomes.
Learner control of pacing can take the form of pause/play buttons, or breaking the animation into discrete units. When using pause/pay buttons, learners should be primed by directing them to pause the animation when they need to think about what has just been presented. Whether or not they do pause seems to be irrelevant; by using this kind of priming, the learner actively watches the material as opposed to just 'watching a movie'. Similarly, by breaking the anmation into segments, the implication is that each segment has a point that should be gleaned.

Reference:
Hasler, B., S., Kersten, B., and Sweller, J. (2007). Learner Control, Cognitive Load and Instructional Animation. Applied Cognitive Psychology. 21, p713-729.