Even small effect sizes can be meaningful, particularly if they are devoted to initiatives that save lives. For example, Robert Rosenthal and M. Robin DiMatteo (2001) demonstrate that the effect size of taking a low dose of aspirin in preventing a heart attack is 0.07—a small fraction of a standard deviation—yet this translates into the result that thirty-four out of every one thousand people would be saved from a heart attack by using a low dose of aspirin on a regular basis.
The use of the common statistic for effect size helps busy teachers and school administrators evaluate alternative strategies and their impact on achievement compared to variables outside teachers’ and students’ control. For example, some of Hattie’s findings include the influence of the following on student achievement (Hattie, 2009).
• Preterm birth weight (0.54)
• Illness (0.23)
• Diet (0.12)
• Drug use (0.33)
• Exercise (0.28)
• Socioeconomic status (0.57)
• Family structure (0.17)
• Home environment (0.57)
• Parental involvement (0.51)
Most teachers would view these factors as outside of their control, although some would certainly argue that schools can do a better job of influencing diet, drug use, exercise, and parental involvement. During the eighteen hours every day that students are not in school, students and families make many decisions that influence learning in significant ways. But how important are these decisions compared to the variables that teachers and school administrators can control?
The Importance of Feedback
The effectiveness of any recommendation regarding teaching and education leadership depends on the extent to which the professional practices of educators and school leaders have a greater impact on students than factors that are beyond their control. The essential question is, Will this idea have a sufficient impact in helping students overcome any negative influences they face outside of school?
Fortunately, Hattie (2009) answers that question with a resounding affirmative response. He finds a number of teaching and leadership practices that, measured in the synthesis of meta-analyses, are more powerful than personality, home, and demographic factors when considering their impact on student achievement. Examples include teacher-student relationships (0.72), professional development (0.62), teacher clarity (0.75), vocabulary programs (0.67), creativity programs (0.65), and feedback (0.73).
Certainly, Hattie is not the first scholar to recognize the importance of feedback on student achievement. His findings are completely consistent with Robert Marzano’s (2007, 2010) conclusions that accurate, specific, and timely feedback is linked to student learning. Thanks to Hattie’s research, however, we can now be more precise than ever about how important it is. We can say that, based on the preponderance of evidence from multiple studies in many cultural settings, feedback is not only more important than most other instructional interventions but is also more important than socioeconomic status, drug use, nutrition, exercise, anxiety, family structure, and a host of other factors that many people claim are overwhelming. Indeed, when it comes to evaluating the relative impact of what teachers and education leaders do, the combined use of formative evaluation and feedback is the most powerful combination that we have. If we understand that a grade is not just an evaluation process but also one of the most important forms of feedback that students can receive, Hattie’s conclusion should elevate the improvement of grading policies to a top priority in every school.
Hattie (2009) also encourages a broadly based view of feedback, including feedback not only from teachers to students but also from teachers to their colleagues. We should recall that, as a fundamental ethical principle, no student in a school should be more accountable than the adults, and thus our feedback systems must be as appropriate for teachers and leaders as they are for students. Similarly, our standards for administrators, board members, and policymakers must be at least as rigorous as those we create for fourth graders. If that statement seems astonishing, then I invite you to obtain a copy of the fourth-grade academic standards for your area and lay beside them the standards that are officially endorsed for policymakers, such as legislators, members of parliament, members of Congress, or other educational authorities. You can then decide which standards are more demanding.
The Evidence–Decision Gap
It is therefore mystifying that a strategy with so great an impact on student achievement as feedback remains so controversial and inconsistent. It is as if there was evidence that a common consumer practice created an environmental disaster, but people ignored it and persisted in the destructive practice. Of course, that is hardly a hypothetical example, as our national habits—such as persistent use of bottled water, dependence on gas-guzzling cars, and appetite for junk food—illustrate. Rather than embrace the evidence and use filtered tap water, take public transportation, and eat fresh vegetables, we often choose the convenient alternatives that are less healthy for our families and the planet.
In sum, our greatest challenge is how to transform what we know into action. Indifference to research, though also present in medicine, business, and many other fields (Pfeffer & Sutton, 2006a), is particularly striking in education. An alarming example is the persistent use of retention and corporal punishment. In both cases, decades of evidence suggest that these “treatments” are inversely related to student learning. Retention does not encourage work ethic and student responsibility but only creates older, frustrated, and less successful students (Hattie, 2009). Corporal punishment does not improve behavior but legitimizes violence and increases bullying and student misbehavior (Committee on School Health, 2000). Nevertheless, politicians from all parties have excoriated social promotion and urged retention in a display of belligerent indifference to the evidence. More disturbingly, nineteen states and many other nations continue to permit corporal punishment decades after the evidence concluded it was counterproductive (Strauss, 2014).
Equipped with rich literature on the theory and practice of change, educators and school leaders should be fully capable of acknowledging error, evaluating alternatives, testing alternative hypotheses, and drawing conclusions that lead to better results. Instead, personal convictions that are not only antiquated but maybe even dangerous guide decision-making processes. We can be indignant about the physicians of the 19th century who were unwilling to wash their hands, but when the subject turns to education policies, we sometimes elevate prejudice over evidence.
Before we consider what quality feedback is, let us be clear about what feedback is not. Feedback is not testing.
Distinguishing Feedback From Testing
Consider two classrooms, both burdened by large class sizes and students with a wide range of background knowledge and skill levels. The role of the teacher in the first class is to deliver what, as a matter of school-system policy, has been described as a “guaranteed curriculum.” Administrators know that the curriculum is delivered because teachers list the instructional objectives on the board and post the details of the lesson plan supporting those objectives next to the door, where visiting leaders can easily inspect them. In this class, the most important feedback that students and teachers receive is on the annual test administered every spring. This feedback is very detailed, as it determines the success and failure of not only individual students but also the entire school, perhaps the entire school system. Moreover, external companies have established elaborate statistical