Intrinsic cognitive load represents the burden imposed on working memory by the inherent nature of the material. In other words, simple topics require very little processing capacity in working memory, and complex topics demand a large amount of space. For example, it requires considerably more focus to safely drive a semi truck through a rainstorm than to sign your name with a pen on paper. Driving the semi requires attention to many different information inputs (e.g., gauges, mirrors, windshield) and coordinating the requisite motor skills in response; all of this processing is conducted in working memory. Signing one's name takes barely any attention at all (for adults) because it has been done thousands of times before. Thus, the effect of having practiced the skill reduces its intrinsic cognitive load.

But practice alone cannot reduce the intrinsic cognitive load of all tasks. The element interactivity (i.e., coordination among multiple aspects) inherent in some tasks cannot ultimately reduce the task to a trivial activity, even with extensive practice. If that were the case, we should all be capable of becoming skilled airline pilots or successful politicians.

For beginners learning an essential skill, element interactivity becomes problematic and must be temporarily reduced. When learning a language, one first learns the alphabet and then proceeds to acquire simple words or phrases—not complex prose. But one cannot be considered proficient in a language unless one can understand its complex prose. This is an example of element interactivity because understanding prose depends upon not only understanding its nouns, verbs, adverbs, etc., but also how each of them modifies or alters the meaning of other words nearby. Topics or skills that contain element interactivity must at first be oversimplified and then gradually built up to their full complexity before one can successfully deal with the intrinsic cognitive load.

Extraneous cognitive load is the set of mental demands that are irrelevant to the current task. Recall the butterfly display that was distracting Pierre ((Reference))? The butterflies had nothing to do with the directions the teacher was giving Pierre's group, yet Pierre was distracted by his classmates on the other side of the room. His classmates' activity was extraneous cognitive load for Pierre because it was consuming his precious cognitive resources yet not providing any real benefit to him in the task of understanding his teacher's directions.

It is critical to realize that these various forms of cognitive load are additive—that is, they each increase the amount of processing space that is active in working memory. For example, if the intrinsic load is already high, there is not much room for any extraneous load unless the learner decides (like Pierre) to reduce the processing of the intrinsic load and focus more on the extraneous load. Teachers should strive to reduce extraneous cognitive load in their classrooms because students are likely to sacrifice attention to important material and distract themselves with the extraneous stimuli.

Extraneous cognitive load is, for the most part, under the direct control of the teacher. Have you ever seen presentations that were decorated with graphics which were only tangentially related to the content? You probably found yourself sidelined by the images and not paying sufficient attention to the material itself. Because working memory has such a limited capacity, we cannot afford to “clutter up” this valuable space with unproductive ideas that divert attention from more important content. As a teacher, you should make earnest efforts to avoid exposing students to extra “fluff” during learning activities.

Germane cognitive load has been explained in various ways. The explanation I prefer is the more traditional characterization that germane load represents increased demand upon working memory in the service of the learning goal. This can be explained more easily through an example. Most (if not all) languages have forms of expression that are not appropriate for all audiences. For example, in English one would not address the President of the United States in the same informal way as one would address a close friend (“How is your day going, Mr. President?” versus “Hey dude, whazzup?”). The meaning of the utterance expressed to these two individuals may be the same, but the words and intonation are somewhat different. If an international student were learning English, it would be important for the language teacher to communicate not only the meaning of the words (intrinsic load) but also the contexts in which those words are appropriate (germane load). Learning the situations in which certain phrases are most appropriately used goes beyond intrinsic load but could hardly be considered extraneous if one's purpose is to learn the language well.

It goes without saying that beginning learners should not be exposed to germane cognitive load; the intrinsic load for many tasks is of sufficient complexity that beginners cannot handle any additional processing burdens. However, as learning proceeds and the intrinsic load becomes more and more automatized, teachers can add aspects of additional complexity that enhance students' understanding of the material in a germane way.