The Hess Cognitive Rigor Matrix

April 11, 2014

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A brief history of the Hess Cognitive Rigor Matrix


Today various educational and testing organizations in the US and other countries now use the Hess Cognitive Rigor Matrix in training materials for their professional development and curriculum work. So where did the Hess CRM come from?


Karin Hess’ quest for a better – and more sophisticated - interpretation of cognitive rigor began in 2005 when she first combined two existing models for describing rigor and deeper learning that were widely accepted in the fields of education and assessment in the United States. Although related through their natural ties to the complexity of thought, Bloom’s thinking levels and Webb’s depth-of-knowledge levels differ in scope, application, and intent (Hess, Carlock, Jones, & Walkup, 2009). The result of this early thinking was the Hess Cognitive Rigor Matrix (CRM) - a model that superimposed Bloom's Taxonomy with Norman Webb's Depth-of-Knowledge levels. The Hess CRM assists teachers in applying what cognitive rigor might look like in the classroom and guides test developers in designing test items and performance tasks.  Content-specific descriptors in each of the Hess CRMs are used to categorize and plan for various levels of abstraction – meaning an analysis of the mental processing required of assessment questions and learning tasks.


The original Hess CRMs for ELA-Social Studies and mathematics-science were used by The Standards Company LLC to conduct a large-scale analysis of assignments given to students in Oklahoma and Nevada over a 3-month time period. Work samples of homework assignments, test, quizzes, etc. were analyzed using the Hess CRM to develop density plots that visually described the level of complexity (or lack of it) in most work assigned to students. (For more on this research study, see “What exactly do fewer, clearer, and higher standards really look like in the classroom?” by Hess, et al., 2009,


Bloom meets Webb


The development of the Hess CRM began with a thoughtful question from a state-level committee working with Karin on the design of their new large-scale assessment blueprint. Like many states at the time, this state had been using Bloom’s Taxonomy to describe test item complexity for several years. “Isn’t Webb’s DOK model just another way to describe the same thing as what Bloom’s six levels do?” they asked when Karin introduced and suggested that the state use Depth-of-Knowledge level descriptors instead of Bloom.


Karin struggled at the time to clearly articulate the key differences that she was seeing. On the plane home, she began to examine each model in greater depth and experimented with where the two models seemed to intersect. Eureka! A rigor matrix is born…Deeper learning/ thinking is not about verbs, taxonomies, complex texts, or what we have generally thought of as “higher order” thinking. There was a significant difference between “analysis light” (DOK 2) versus deep understanding of a topic or concept (DOK 4).


 In 1956, Bloom’s original taxonomy was developed as a way to classify intellectual behaviors important in learning and assessment. In 2001, Bloom’s revised taxonomy applied two dimensions - cognitive processes (the verbs) and the knowledge (the nouns) used – in order to articulate educational objectives. This restructuring of the original taxonomy recognizes the importance of the interaction between the content taught – characterized by factual, conceptual, procedural, and metacognitive knowledge – and the thought processes used in learning. Still, even the revised version of Bloom has some shortcomings: sometimes verbs/processes can seem similar in differing levels; and thinking process, even at higher levels, do not necessarily translate to deeper understanding of content. Compare-contrast (DOK 2) can be a much “lighter” form of analysis than analysis of theme development in one (DOK 3) or more texts (DOK 4). Most importantly, Bloom’s levels are somewhat generic to different content areas; yet we know that the mental processing used for analyzing a literary text, for example, does not require the same organizational schemas and mental engagement as analyzing in mathematics or science or the arts.


Webb’s Depth of knowledge (DOK) levels form another important perspective of cognitive complexity (Webb, 1997, 2002). Webb describes his DOK framework as “nominative” rather than as a taxonomy. DOK levels name four different ways students interact with content. Each level is dependent upon how deeply students understand and engage with the content in order to respond, not simply the type of thinking (verb) used. The Webb levels do not necessarily indicate degree of “difficulty” in that Level 1 can ask students to recall or restate simple or much more complex information, the latter being more difficult. Conversely, deeper understanding of a concept is required to be able to explain how/why a concept works (DOK 2), apply it to real-world phenomena with justification and supporting evidence (DOK 3), or to integrate one concept with other concepts or other perspectives (DOK 4) to produce novel ideas or solutions. DOK descriptors in the CRMs provide content-specific examples that illustrate how students might move towards deeper understanding with more complex or abstract content.


Next Generation CRMs


The first Hess CRMs started with the six Bloom’s Taxonomy levels along the rows of the matrix and the four Webb's Depth-of-Knowledge levels along the columns; however Karin has found that some content areas do not readily lend themselves to integrating Bloom’s Taxonomy with DOK.  And as Karin has worked with many states, school districts, and educational organizations over the years, some additional fine-tuning has been needed to make the CRMs more useful. In her latest materials, Karin has revised and expanded the Hess CRMs to better clarify and encompass new content descriptors and more content areas. Currently there are several tools available to educators in Module 1 of Linking Research with Practice: A Local Assessment Toolkit to Guide School Leaders (2013). The Toolkit now includes: Tool 1 – Close Reading/Listening/Viewing; Tool 2 – Math-Science; Tool 3 – Writing/Speaking; Tool 4- Social Studies/Humanities; and Tool 5 – Fine Arts. These tools are currently available at In 2015, a World Language CRM, a Health and Physical Education CRM, and a Career-Tech/CTE matrix were added. These new tools, as well as the Fine Arts (Tool #5), integrate Webb’s four DOK levels with content specific practices that may or may not resemble the Bloom levels. Karin always welcomes your feedback and questions on the use of these tools.

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Karin Hess, Ed.D, is a recognized international leader in developing practical approaches for using cognitive rigor and learning progressions as the foundation for formative, interim, and performance assessments.



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© since July 2014 Karin Hess, Ed.D.