When educators examine the rigor of an activity or when they look for ways to introduce rigor into their lesson plans, they often consult one of two models: Bloom’s Taxonomy—originally developed by educational psychologist Benjamin Bloom in 1956—or Webb’s Depth of Knowledge (DOK)—developed in 1991 by Norman L. Webb, a senior research scientist at the Wisconsin Center for Education Research.
But because Bloom’s Taxonomy is so prevalent and well-known, most educators will begin and end their lesson planning with Bloom’s model alone. And there are still many educators who are not even familiar with Webb’s DOK or who mistakenly believe that Webb’s DOK and Bloom’s Taxonomy are essentially the same. However, by understanding how Bloom’s Taxonomy and Webb’s DOK are different and how the two actually work hand in hand with each other, educators can work from a more complete model to help increase the cognitive rigor of their lesson plans.
In 2009, Karin K. Hess, a nationally recognized expert in content and curriculum across a broad spectrum of areas, superposed Bloom’s and Webb’s models for describing rigor and introduced what is now known as Hess’s Cognitive Rigor Matrix. By combining the two models into this matrix, Hess showed how the two models for rigor could be used together to enhance lesson planning and other classroom-level processes. But to fully understand how the two models function together, you must first understand how they differ.
Bloom’s Taxonomy categorizes activities based on their level of cognitive complexity, but it does not define the types of thinking necessary to process information during a given activity. That’s where Webb’s DOK comes in. Webb’s DOK defines the depth of understanding that is demonstrated based on the complexity of tasks within an activity.
A more comprehensive model for cognitive rigor
“Because students need exposure to novel and complex activities every day, schools in the twenty-first century should prepare students by providing them with a curriculum that spans a wide range of the cognitive rigor matrix” (Hess, 2009). Working from Bloom’s model alone, two tasks may fall into the same category and seem very similar, with little to distinguish them though they may vary greatly in rigor and complexity.
But by implementing Hess’s Cognitive Rigor Matrix, educators can look at both the level of cognitive complexity an activity requires and the tasks associated with a particular level of understanding. This allows educators to more accurately analyze and differentiate tasks, thus enabling them to create more effective lesson plans. And by challenging students to use information in new and complex ways, educators can foster deeper levels of learning and understanding.
Hess, Karin K., Ben S. Jones, Dennis Carlock, and John R. Walkup. “Cognitive Rigor: Blending the Strengths of Bloom’s Taxonomy and Webb’s Depth of Knowledge to Enhance Classroom-level Processes.” 2009. Accessed April 1, 2015. http://eric.ed.gov/?id=ED517804.