I had a physics teacher in college whose lectures were so amazing that I often felt like I already knew everything he was saying. It was so clear and organized it almost seemed like common sense.
It seems pretty obvious that utter clarity is a hallmark of truly excellent teaching. There's just one problem: It may not be true. In my case, I had trouble remembering the lectures after they were over. And that’s part of the problem with clarity: According to growing mountain of research, understanding isn't enough. It's the struggle that makes us learn. By making things too clear, teachers can inadvertently prevent students from learning. I explain below that teachers shouldn’t exactly be unclear either. But first, here's some evidence.
The value of ugly fonts
Humans are information processors. On its face, making information easy to processes seems like a good idea for teachers. Researchers Connor Diemand-Yauman, Daniel M. Oppenheimer and Erikka B. Vaughan put this idea to the test.
They convinced a group of high school teachers to change all of the fonts in their PowerPoint presentations and handouts from clear fonts to "disfluent" fonts such as Monotype Corsiva. To be included in the study, a teacher had to be teaching two sections of the same class; one section used normal fonts and one used disfluent fonts. There were six classes in each condition.
When it came time for exams, the control classes were outperformed by the classes that were given the unusual, unclear fonts. Score one for making them struggle.
This finding is amazing. It’s also counterintuitive. One teacher actually rejected the font Haettenschweiler because it was too illegible. Like the other fonts, it proved to be effective. More generally, we are biased to believe that easy processing enhances learning, even when it doesn’t.
Ugly fonts are but one example of "desirable difficulties," that is, learning techniques that make us struggle but help us learn.
Another is spacing — that is, making sure to space study sessions apart across time. Spacing is valuable because we don't learn much from studying something that we haven't forgotten — we learn when we have to struggle to remember. Forgetting is the friend of learning.
Taking tests is another desirable difficulty. People learn more when they’re asked to come up with information themselves rather than when they’re told the information. This may seem somewhat intuitive. But students even benefit from being asked test questions that they can’t answer (if they’re subsequently told the answer)! Again, it's about the struggle.
A study came out recently that combined spacing and testing. Researchers Jason R. Finley, Aaron S. Benjamin, Matthew J. Hays, Robert A. Bjork and I found that not only are tests valuable, but harder tests are more valuable. As spacing (i.e., the time for forgetting) increases, error rates increase during study, but long-term learning increases as well.
What's a teacher to do?
These studies all point to the same conclusion: Making instruction clear and easy can give students an illusion of learning, but it doesn't necessarily make them learn more. Struggling with the material has value.
Let's be very, very clear: A lecture that’s just confusing is a bad lecture. Getting students confused might have some value. Leaving them confused is an absolutely terrible idea. Confusion can lead to deeper understanding but only if it is followed by clarification. Reach a solution, or better yet, guide your students so they can reach it themselves.
There's a wonderful video about science instruction that talks about the value of confusion. One thing it points out is that if you don't make people see their own misconception, they keep believing those misconceptions. That’s why I started this essay by concluding that good teaching is clear teaching. (Cute, right?)
Telling people the facts isn't always enough. They have to work through the information for themselves. Sometimes the hard way is the easy way.