Of the factors that affect the quality of one's teaching, I know of few as powerful as the teacher’s understanding of the content being taught. When we deeply know what we’re teaching — whether it's language conventions or solving equations or phonemic awareness or how to shoot a basketball — we’re more likely to teach it well, to use apt analogies, to check for understanding and so on.
On the other hand, when our understanding is vague, incomplete, or superficial, we’ll bumble through the teaching — and our students will scratch their heads.
In 2004, researchers Anthony J. and Mary Dekonty Applegate dubbed this idea the Peter Effect, based on a line in the Bible's book of Acts where Peter tells a beggar that he can’t give money because he doesn’t have any. In the paper, the Applegates argue that teachers who do not read for enjoyment themselves are unlikely to produce a recreational reading life in their students. We cannot give what we don't have. We can teach well only from that which we understand well. The Peter Effect.
In a later paper, researchers at Texas A&M and elsewhere demonstrated that the Peter Effect applies to teacher preparation, too. These researchers showed that when educators participated in a training on research-based reading instruction (called “the science of reading” in Education Week’s recent “Getting Reading Right” report and in previous reporting by Emily Hansford at APM), their students ended up performing better on the state reading assessment than both their peers and the educators who hadn’t gone through the research-based reading instruction training.
Both papers demonstrate how important teacher understanding is. They allege that even when we teachers have great intentions and even when we put forth massive effort, we can persist in poor outcomes when our understanding is weak. That second paper's chief finding bears repeating: teacher prep educators scored worse on a reading assessment than teacher prep students who had been taught by more knowledgeable teacher prep educators.
What the Peter Effect suggests is that our professional development must focus not just on teacher skills but on teacher knowledge. For whatever reason, new teachers in the United States do not possess strong content knowledge and strong knowledge of the cognitive science of learning. And so, our professional development must focus on systematically remediating for these things.
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