UDL assumes, based on cognitive neuroscience, that no two learners are alike. Designing for a "mythical" average (as Todd Rose explains in the Myth of Average) is to design for no-one.

 

If we asked children to run a race and then provided everyone with the same, average sized shoe, it would soon become apparent the majority would struggle to finish the race. If we also assessed running abilities based on this "test", we'd quickly recognize its inherent bias. 

 

As Dr. Rose notes, we immediately understand foot size variability but, as evidenced by our education system, struggle to address learner variability. 

 

UDL believes we must plan for learner variability from the outset so that less students struggle with one-size-fits-all assessment, curriculum, methods and materials.