Dougherty Stahl on Constrained and Unconstrained Reading Abilities
[C]onstrained abilities consist of a limited number of items and thus can be mastered within a relatively short time frame. Unconstrained abilities are learned across a lifetime, broad in scope, variable among people, and may influence many cognitive and academic skills. These abilities are never fully mastered because proficiency varies by text difficulty, genre, task, and instructional context. ...
Name writing, alphabet knowledge, concepts about print, high-frequency word lists, and phonics can be considered highly constrained abilities. First, they each consist of a finite number of items to be learned, so mastery occurs within a short time span. For example, name writing is the most highly constrained ability listed. Although some children may learn to write their names at age 3, and others may not learn to write their names until age 5, all children learn to write their names within a short time period contingent on complexity of name, level of instruction, and mastery criteria. Characteristic of highly constrained abilities, knowledge is universal.
Children only vary in their ability to perform highly constrained tasks within a short window of time. Both before and after the window, there is minimal variability. Consider phonics, a skill that is less constrained than letter knowledge but more constrained than oral reading fluency. In general, this finite set of high-utility letter–sound patterns grows from no knowledge to mastery between kindergarten and third grade ... Constrained skills need to be taught to levels of automaticity because they are necessary but insufficient for the development of more sophisticated, complex reading abilities. ...
However, if school personnel are not cautious, then these easily quantifiable skills can tend to dominate school assessment systems. Tests of isolated skills reflect mastery of constrained abilities rather than making sense of texts. ... If phonics dominates early literacy instruction, the massed time required for unconstrained abilities is compromised. This creates a particularly vulnerable situation for English learners and is likely to result in a higher price at the upper levels in more general reading abilities. ...
Unlike constrained abilities that are taught to universal, easily measured levels of mastery, unconstrained abilities are difficult to quantify, and knowledge increases over time but not to levels of simplistic mastery. This makes both teaching and assessing unconstrained abilities more complex and time consuming. For example, vocabulary knowledge is acquired across a lifetime. Word knowledge is not known or unknown as a letter name is; rather, knowledge about words and one’s ability to use vocabulary is acquired incrementally. Rather than applying intense teaching for automaticity and accuracy, repeated and varied opportunities for reading, writing, and incorporating the words in speech are required, which result in increasingly refined use of the target vocabulary
... The least constrained skills are not bound to such finite limits and structures; they typically call for cognitive flexibility, critical analyses, and contextual variation. ... Collaborative learning should occur among students with different ability levels, background knowledge, and skill sets. This is the curricular area where engagement, student choice, and authenticity seem to play important roles in growth and literacy achievement.
Dougherty Stahl, K.A. (2011). Applying new visions of reading development in today's classrooms. The Reading Teacher: A Journal of Research-Based Classroom Practice, 65(1), 52–56. doi: 10.1598/RT.65.1.7 || Link