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Carnegie Units

time learning school schools

Adopted in the early 1900s to both standardize and ensure the quality of high school education, the Carnegie unit is viewed almost a century later by critics as an impediment to flexibility. Yet, for all of its limitations, the Carnegie unit remains the putative guarantor that students have invested in each of their courses an amount of time that warrants the credit that so many colleges and employers presume represents learning.

In fact, the search for the answer to the elusive question of how much learning results from each course gave birth to the Carnegie unit, and keeps the approach alive as a surrogate for knowledge gained. In another era, college admissions officers–especially at selective colleges–concerned themselves mostly with applicants from private preparatory schools, believing that they needed to become familiar with the quality of only those few schools. Even at a state institution such as the University of Michigan, it was the responsibility of the faculty to oversee academic standards at the secondary level. Admissions officials and faculty everywhere, however, could not keep track of the standards at new public high schools that proliferated across the country during the first decades of the 1900s.

Thus, the Carnegie Foundation for the Advancement of Teaching encouraged the adoption of what came to be known as the Carnegie unit, which equates seat-time with learning. Each unit represented about 130 instructional hours. The Carnegie Foundation defined a unit as a course that met for a period each school day for about 50 to 55 minutes. The Carnegie unit continues to influence much that is crucial to teaching and learning in high schools–the length of the class period, the school day and the school year, as well as the time expended to receive a diploma. The unit affects the very way that knowledge is organized for instructional purposes, discouraging interdisciplinary teaching because of the difficult question of deciding how many units to attribute to each discipline. Those who would organize and convey knowledge differently inveigh against the "tyranny" of the Carnegie unit, asserting that seat-time is not a proxy for learning and that secondary schools must be flexible to engage students and to heighten learning. The following developments add to the challenge:

  • Block scheduling
  • Out-of-classroom field experiences
  • Distance learning and independent study
  • Portfolios and other performance-based assessments

Under block scheduling, a course meets for a specified number of hours; but, this number may vary from that of traditional courses because of the way the time is arranged. Out-of-class experiences involve time configurations that only remotely relate to seat-time. Distance learning made possible by technology, in combination with independent study, tends to free students to spend as little or as much time as they require to cover the material. Performance-based assessment may be used in conjunction with the Carnegie unit, or it may argue for an appraisal of learning without regard for seat-time. Aspects of school reform underscore the idea that secondary students might benefit from less reliance on Carnegie units. The Coalition of Essential Schools, for instance, advocated a more limited but more intense curriculum under the motto of "Less Is More." Furthermore, the move to integrate subject matter, especially at small alternative high schools, made it less clear how to satisfy the unit requirement. But no widely accepted alternative guarantor of quality emerged by the beginning of the twenty-first century.

In fact, demands for accountability helped preserve the Carnegie unit. Taxpayers wanted assurances that the $350 billion a year they bestowed on public schools was not squandered. Colleges sought methods to compare applicants and to gauge the extent of their preparation. David Tyack and Larry Cuban cited the "interlocking reasons" (p. 107) that defenders of the status quo gave for regarding the Carnegie unit as part of a system that could not withstand tampering. This system–the time devoted to each class and each course, the departmental organization, the lecture method of teaching–was likened by its guardians to the building blocks that support an entire structure. Remove one, they said, and the stability of the others, and of the high school itself, was imperiled. Colleges and universities, prodded by the Carnegie Foundation, forced the unit requirement on secondary schools. It may be that altering or altogether eliminating the Carnegie unit will ultimately depend on whether educators can agree on a more meaningful symbol for knowledge gained in secondary education.


LAGEMANN, ELLEN CONDLIFFE. 2000. An Elusive Science: The Troubling History of Education Research. Chicago: University of Chicago Press.

MAEROFF, GENE I. 1993. "The Assault on the Carnegie Unit." Education Week October 13, p. 36.

TYACK, DAVID, and CUBAN, LARRY. 1995. Tinkering toward Utopia: A Century of Public School Reform. Cambridge, MA: Harvard University Press.


Categorization and Concept Learning - Form and Format of Conceptual Knowledge, Theories Of Category Learning, Conceptual Change in Children [next] [back] the Carnegie Classification System - History and Updates, Classification Categories In (2000), Classifications (1994 )

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