The group that invented the Carnegie unit—also known as the credit hour—more than 100 years ago announced this week that it had re-examined the measurement’s usefulness and found that, while imperfect, it still serves a vital administrative purpose and has not been a major obstacle to innovation in schools.
The Carnegie unit initially was developed as a way to standardize the amount of instruction students received, in part to determine if high school students had been given enough preparation for college. American high schools typically award one Carnegie unit of course credit for 120 hours of instruction. In recent decades, critics of the measurement have said that, given the nation’s shifting focus on achievement and advances in technology making it possible for students to learn at their own pace, the Carnegie unit has become obsolete.
Developed in 1906 and named for industrialist Andrew Carnegie, who established the Carnegie Foundation for the Advancement of Teaching, the Carnegie unit is a measure of the amount of time a student has studied a subject.
Per its original definition:
1 hour of instruction x 5 days a week x 24 weeks = 120 hours of contact time with an instructor = 1 standard Carnegie unit
Most public high schools use this 120-hour standard to award course credit. (Though today, high school classes tend to last less than an hour and be held over a 36-week period.)
A typical high school student earns 6 to 7 credits per year over 4 years. Most states require a minimum number of Carnegie units for graduation.
SOURCE: Carnegie Foundation for the Advancement of Teaching
About 40 states now have policies that allow students to replace Carnegie units with demonstrations of competency or out-of-school experiences for academic credit, according to the, a Denver-based research and policy organization.
In fact, three states—Maine, New Hampshire, and Vermont—have gone even further, requiring schools to use competency measures rather than seat time to assign credit. (New Hampshire has been piloting this practice for more than a decade, while the Maine and Vermont requirements go into effect for the classes of 2017 and 2020, respectively.)
However, in its report released Jan. 29, the Stanford, Calif.-based—which spawned the Carnegie unit in 1906—defended the unit as a necessary “common currency” among education institutions. “The Carnegie unit’s value in providing a minimum instructional standard for all students shouldn’t be underestimated,” it states. “If the quality of teaching and learning already differs dramatically from class to class (and from online platform to online platform), the level of learning might vary even more substantially in the absence of the Carnegie unit.”
In conducting the study, which was supported by the William and Flora Hewlett Foundation, the Carnegie Foundation spent 18 months doing archival research, visiting K-12 and higher education institutions, and interviewing educators, administrators, union representatives, policymakers, and other practitioners. (The Hewlett foundation also supports coverage of “deeper learning” in Education Week.)
In K-12 schools, the Carnegie unit affects everything from daily schedules and course sequences to staffing decisions and instructional strategies. In higher education, it’s also a factor in determining billions of dollars in eligibility for federal financial aid, the report states.
“The system continues to rely on it because, in large part, the Carnegie unit is the system,” Noelle Ellerson, the associate executive director for policy and advocacy for the Alexandria, Va.-basedsaid in an interview. She was not involved in the report.
On a media call, one of the report’s authors, Elena Silva, emphasized that the Carnegie unit “is a strong administrative tool for the system. It continues to be that. It’s also a minimum standard for instruction that ensures all students get at the very least a minimum amount of time learning.”
What the Carnegie doesn’t do, though, is give a sense of how much students have learned.
“It’s a huge shift to turn from minutes to, ‘Are kids learning?’” said Susan Patrick, the president and chief executive officer of the, who is not associated with the report. Moving students along in school based on the amount of time they put in, rather than content mastery, “essentially ensures they have these Swiss cheese holes in their learning,” she argued.
The Carnegie unit was never intended to be a measure of learning, Ms. Silva, a senior associate at the Carnegie Foundation, said on the media call. “It’s just a time-based measure of exposure,” she said. “It’s one of the few guarantees, if not the only one we have in American education, that all students have the most basic resource: time to learn.”
The unit is also not as much of a hindrance to new methods of instructional delivery as critics have suggested, according to the report. “There is more opportunity to innovate than some suggest and there’s a lot more innovation going on than one might think,” Thomas Toch, another of the report’s authors, said. “It’s going on despite the presence of the Carnegie unit.”
According to the report, many states “are modifying their laws and regulations to permit staggered staff schedules, online learning, Saturday schooling, and a host of other variations in how the school day and year are organized.” And some states are doing so “under existing statutory and regulatory flexibility,” it says.
The report walks a fine line throughout, lauding efforts toward making learning more transparent and flexible, admitting the Carnegie unit can be a barrier—though not an insurmountable one, and ultimately maintaining the need for the time-based credit assignment.
For instance, the group says it’s in favor of efforts that take student learning into account. But the report also states that competency-based approaches could increase educational disparities by “speed[ing] the progress of more accomplished and affluent students (who tend to have many out-of-school learning experiences and are often tutored over academic hurdles), while their peers are left to struggle and possibly fall further behind.”
The report also says there’s little evidence that education would improve under a competency-based approach. “These innovations hold great promise, but we need to be careful not to think more innovation equals more learning,” said Mr. Toch, a senior partner at the Carnegie Foundation. “We talked to consultants working with New Hampshire, and one said looking at districts across the state you could find the good, the bad, and the ugly when it comes to competencies and measures of them.”
The authors point to the common-core-aligned assessments, which debut this spring in most states, as promising methods for measuring student learning on a common yardstick. However, the report also notes that these tests have been costly, and that expanding such a testing system with performance-based measures (such as essays and projects) would pose logistical difficulties.
Seeking a Substitute
Mark F. Smith, a senior policy analyst for the Washington-based, which was influential in the development of the Carnegie unit a century ago as well, said the credit hour still has value, but only because the field hasn’t identified a better replacement. “It provides some basis of comparison, some agreed upon standard, but given all the differing approaches that are out there now, it’s not enough,” he said. “I think we’re all struggling with how to replace it.”
For Ms. Patrick of iNACOL, the answer is simple. Keep the Carnegie unit, but redefine it in terms of student learning. The purely time-based measure, she said, “has outlived its utility.”
The Carnegie Foundation’s vision is that even if a new agreed upon student-learning measure is developed, the Carnegie unit would continue “to serve as a common administrative currency.”
As Carri Schneider, the director of policy and research for, a consulting and advocacy group for K-12 digital learning, sees it, a diploma would be worth more if it indicated more than just how much time a student spent in class. But schools have a long way to go before they can get rid of the Carnegie unit. “So much of the system right now is still built around time,” she said. “I don’t think we can just close the door on time immediately.”
That said, Ms. Schneider believes it will eventually be phased out.
“I think it’s really the only way,” she said. “If the Carnegie unit was serving everyone well and everyone was coming out with a high school degree and was ready for college and careers, I don’t think we’d be having this discussion. But the system’s failing a lot of kids.”
Coverage of more and better learning time is supported by a grant from the Ford Foundation at www.fordfoundation.org. Education Week retains sole editorial control over the content of this coverage.
A version of this article appeared in the February 04, 2015 edition of Education Week as Carnegie Unit Is Still Useful, Report Argues