The Myth of Average.
During the industrial revolution, statistical averages became the benchmark for measuring human potential. The "average" person is born. That "average" is considered "normal." Working with an average enables scale. Averages are used to design and define everything we create to provide broader access to products and services, including education and learning environments.
The problem is that "average" doesn't exist. Modern science shows us that, because we are highly variable, averages don't effectively measure individual talent. All of us have a jagged learning profile. If we measure our individual potential the result will be a unique collection of strengths and weaknesses for each of us.
Learning environments designed on average are actually designed for nobody. Instruction designed for the "average" destroys talent. We need to incubate and grow talent of the broadest kind to thrive in the 21st century.
We need to design to the edges.
There is no such thing as an "average" student. All students vary in memory, curiosity, language, vocabulary, perception, interests, culture, background, etc.
Watch the online video "The Myth of Average" by Todd Rose, to understand why we must design instruction that is flexible and adapts to individual student learning profiles.