​​​​The Trouble With Making Assumptions, or “What’s That On Your Head?”

Steven B. Zwickel 

September 30, 2026

A few years ago I was invited to give a presentation to a group of graduate students at the University of Wisconsin. These bright young people were experts in their chosen fields and working their way towards Masters and PhD degrees. They knew all the facts and figures involved in science, math, technology, engineering, etc. and they were now expected to give brief presentations to members of the public who stopped at their exhibits at a Science Day event at the university. My task was to help them give meaningful technical presentations without overwhelming people who visited the event.

Before I began, I asked them to explain what they planned to talk about. It was immediately obvious that they really knew their stuff. What was also obvious was that they had trouble translating these highly technical topics for people who were not university professors.

I put a top hat on my head as a demonstration and told them this story about beaver hats:

• In grade school we studied American history and we were told that one of the major draws to North America for European settlers was the large population of beavers. From the time of the earliest European settlements trade in beaver pelts became a major part of the colonial economy. 
• Our teachers and textbooks explained (sort of) that Europeans were crazy about beaver hats and demand for beaver skins almost drove North American beavers to extinction.
• In my 9-year-old imagination, I envisioned all those Europeans walking around London, Paris, Rome, etc. wearing beavers on their heads. My ideas were based, of course, on having watched Davy Crockett on TV wearing a “coonskin” hat. I assumed, wrongly, that the Europeans  just plopped a dead beaver on their heads. No one corrected me.
• Many, many years later, we took a trip to the Green Bay area and stopped in Oneida to visit the Oneida Nation Museum. As I walked through the exhibits I came to one devoted to the beaver skin trade. It explained in detail how the pelts were treated to make felt. The fine beaver hairs were pressed together to create a silky fabric that was used to make all kinds of hats. {See https://oneida-nsn.gov/}
•  After 60 years I finally learned that no one in Europe actually plunked a beaver on his head. {Now, of course, you can read all about it online: <https://en.wikipedia.org/wiki/Beaver_hat>}

The lesson I was trying to teach the grad students was this: Do NOT make assumptions about what your audience knows. As an expert you have an obligation to make information accessible to your audience, no matter if you are talking to professors, business executives, or ordinary members of the public.

"Modifications of the beaver hat"comes from an illustration in "Castorologia, or the History and Traditions of the Canadian Beaver" 1892, Martin, Horace T.