Challenging The Average

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Ross Morrison McGill founded @TeacherToolkit in 2010, and today, he is one of the 'most followed educators'on social media in the world. In 2015, he was nominated as one of the '500 Most Influential People in Britain' by The Sunday Times as a result of...
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Why do we compare one student’s ability against an overall average of everyone else?

Surely we should be evaluating one student’s performance against another if we wish to compare like for like, not evaluate one versus, say 99 other students.

Over the past 3 months, I’ve been challenging my perceptions and bias of teaching students by ability – or at least evaluating one student’s performance against another – as this is what I’ve always done since teacher training in 1993. I’m starting to believe what we do in our schools is largely outdated and designed for the benefit of the teacher, not the student. You can read my view here on Popping The Differentiation Bubble.

Are students “jagged”? This is a term coined by Harvard Professor Todd Rose, who believes most human characteristics, from size to intelligence, consist of multiple dimensions which are weakly related to one another, if at all .  A principle he calls “jaggedness”.


In the late 1940s, the US Air Force had a problem. Its pilots were crashing their warplanes too often. After ruling out pilot error and faulty mechanics, the main hypothesis became that the average American pilot had outgrown the cockpit, which was designed during the First World War.

In 1950, officials commissioned a new study to measure 140 dimensions of the human body to determine the new “average pilot.” Over 4,000 young pilots had their height, chest circumference, and other measurements taken for this endeavour. The “averagarian” thinking at the time was that a majority of pilots would measure near the average on most dimensions.

One researcher doubted this approach. Lt. Gilbert S. Daniels calculated the average of 10 physical dimensions believed to be most relevant for cockpit design and determined how many pilots measured near the average for all dimensions. Daniels himself was stunned by the actual number. Zero. Out of 4,063 pilots, not a single one fell within the average 30 percent on all 10 dimensions. (Cited here and in the book, The End Of Average)

As Rose says in his book, The End Of Average, “If you’ve designed a cockpit to fit the average pilot, you’ve actually designed it to fit no one.”

The End of Average

The biggest reason differentiation is a myth, is the way teachers are deployed in our classrooms. Bring “together several students who struggle to learn, along with a smattering of gifted kids, while adding a few English-language learners and a bunch of academically average students and expect a single teacher to differentiate for each of them.”

The second reason? We are not really sure what we are differentiating. It may be a worksheet, the curriculum, 30 students in one class versus another 30 in another; one student with a teaching assistant and another 4 or 5 kids requiring literacy intervention. The conclusion to ‘Differentiation Doesn’t Work‘ suggests “differentiation might have a chance to work if we are willing, as a nation, to return to the days when students of similar abilities were placed in classes with other students whose learning needs paralleled their own.”

However, I disagree, but I’m not quite sure what the solution is either.

The Cause

In The End Of Average, Harvard graduate and author, Todd Rose highlights the work of American psychologist, Edward Thorndike. He singlehandedly defined education as we know it. His definition of the purpose of schools and education was to sort students by talent; to predict how a student will perform. Rose writes that “it is deeply ironic, that one of the most influential people in the history of education, believed that education could do very little to change a student’s ability and was therefore limited to identifying those students with a superior brain.”

Thorndike opposed the idea that learning should reflect nature, which was the main thought of developmental scientists at that time. He instead thought that schooling should improve upon nature. The Law of Effect.

Thorndike invented a convenient metric for evaluating student performance. That by collecting quantitative information, we could help teachers and educators deal with practical educational problems in the classroom. This now results in those most likely to succeed and those most likely to fail.

I wonder how many of us have been on the receiving end of this metric?

Liz Carson explains more in her post, The Average Student Does Not Exist in which she explains how “in high-stakes testing, student performance is most commonly judged by one’s relation to the average total score”.

Our team analyzed the results from a past final exam taken by 1506 students in John DeNero’s UC Berkeley Computer Science 61A course. It consisted of 7 questions, 26 subquestions, and 154 rubric items*, with a mean score of 46 out of 80 total points.

Over the past century, we have perfected the education system and as Rose suggests, “it runs like a well-oiled machine squeezing out every possibility.” We may believe that our teachers can meet the needs of children over a longer period of time, and we would obviously aspire towards this as teachers, but to consider that it is possible in a single lesson – particularly under observation – is downright ludicrous!

  1. Thomas B. Fordham Institute’s Michael Petrilli, University of Virginia – All Together Now?
  2. High Achieving Students – Fordham Institute, 2008.
  3. From laws of learning to a science of values: Efficiency and morality in Thorndyke’s educational psychology“. American Psychologist 53 (10): 1152, Beatty, Barbara (1998).

4 thoughts on “Challenging The Average

  1. Todd Rose’s book is an excellent reminder of why securing an average is a search up a blind alley. Differentiation, if that means providing differing ways in which knowledge and skills may be acquired, may be an appropriate activity; if it means dumbing down and stretch and challenge simultaneously that’s probably an unedifying purpose. So much successful learning arises when individual and group purposes conjoin; when inappropriate comparisons are made, why does that help?

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