The Cognitive Load Theory is a theory about learning built on the premise that since the brain can only do so many things at once, we should be intentional about what we ask it to do.
It was developed in 1998 by psychologist John Sweller, and the School of Education at New South Wales University released a paper in August of 2017 that delved into theory. The paper has a great overview–and an even stronger list of citations–of the theory. They also, obviously, define and explain it:
‘Cognitive load theory is based on a number of widely accepted theories about how human brains process and store information (Gerjets, Scheiter & Cierniak 2009, p. 44). These assumptions include: that human memory can be divided into working memory and long-term memory; that information is stored in the long-term memory in the form of schemas; and that processing new information results in ‘cognitive load’ on working memory which can affect learning outcomes (Anderson 1977; Atkinson & Shiffrin 1968; Baddeley 1983).’
Put another way, the cognitive load theory says that, because short-term memory is limited, learning experiences, should be designed to reduce working memory ‘load’ in order to promote schema acquisition.
Since both can’t be done well at the same time, teachers can be specific about not just what is being learned (e.g., content knowledge versus procedural knowledge) and the sequence of the learning (e.g., learn about a ‘thing,’ then how that ‘thing’ works, then how to use that ‘thing’ critically and creatively) it is, but also the nature of what’s being learned (e.g., domain-specific knowledge and definitions versus design thinking through knowledge and definitions).
Cognitive load theory supports improved teaching and instructional design by allowing educators to plan for and design the learning ‘circumstance’ and the sheer volume of tasks, ideas, steps, teaching and learning materials, lesson objectives, metacognitive demands, and other ‘bits and pieces’ of teaching.
Specifically, by simplifying and prioritizing, the cognitive load theory encourages the teacher to emphasize and teach what matters most–or at least prioritize those ideas and skills (in the form of learning objectives) that can otherwise be lost in the neurological ‘bottleneck’ between working and long-term memory and allowing for a more germane (schema-related) cognitive load.