One of the best things that ever happened to me began as a nightmare.

In eighth grade (equivalent to Year 9 in England), sports were the sun around which my life orbited. Every single day of the year, I played American football, basketball or baseball. And I was good. I was small but fast, and I could throw. That’s why I was playing quarterback during gym class on the day that changed everything.

My team had just scored a touchdown. In this schoolyard football, instead of a post‑touchdown kick-off, a member of the scoring team would throw the ball as far as they could to the other side of the field for the receiving team to return. As QB, I was the thrower.

The shock of what happened next erased some of the details from my memory.

I assume I carefully arranged my fingers on the laces of the ball, as always, and patted it a few times. I’m sure I must have taken a running start in order to heave the ball as far as possible. I must have taken the customary hop‑skip‑jump before a long throw, dropped my right hand back and down, faced the sky and launched the ball with all my middle school might.

I think there was a gruesome sound, but the next thing I remember for sure is that I was on my knees in the grass. I remember feeling dizzy and wanting to throw up, and little sparkles winking in and out of existence in my peripheral vision. Something hideous had happened to my arm.

At the hospital, we learned the humerus bone in my upper arm had fractured in a spiral, the upper and lower parts completely separated. A doctor guessed that I’d had a hollow area inside my bone that weakened it, but said that we would never know for sure.

Learning through constraints

It hurt, of course. A lot. But worse than the pain was that I had to have my arm put in a cast all the way from shoulder to hand and strapped to my torso.

For months, I had to sleep sitting up. I had to go to school wearing baggy shirts (stylistically fine at the time!) with one empty arm hole. I was embarrassed, uncomfortable and defenseless in a rowdy school.

Worst of all, sports weren’t just over for the season. I was barred from contact sports for a year, which meant I wouldn’t be able to play football in my freshman year in high school. Which meant, in turn, that the only reason to go to school was...school.

It would be an understatement to say that I wasn’t particularly interested in school in eighth grade, least of all French class. There were quizzes where we’d listen to audio of native speakers and have to follow what they said well enough to fill in blanks on a worksheet that tracked the conversation.

With my writing hand strapped to my torso, I couldn’t keep up. So I devised a strategy. I used mnemonics - long before I had any idea what that word meant. When I heard a French word that went with a blank, I associated it with some image (sports!) in my head, and then linked that image to another image (probably more sports!) for the next word I had to remember.

Suddenly, I found it easy to memorise all of the words for the blanks. When the audio ended, I just went back and filled them all in from memory, writing slowly with my left hand. I actually did better on the quizzes than I had before, when I was using my dominant hand and scrambling to try to fill in the blanks as the audio whizzed by.

Long after my arm healed, I kept using mnemonics - in every class, all the way through grad school. Today, when I have to give a presentation, I have no trouble memorising a fast‑paced, hour‑long talk.

It started because I had to pass those French quizzes when I couldn’t use my right hand. The limitation of my broken arm helped me overcome the limitation of my working memory.

The following year, since I was prohibited from playing football, a gym teacher suggested I run cross‑country to stay in shape. I was uninterested in the sport. But I gave it a try. As it happened, I loved the coach, the guys on the team and the feeling of tangible fitness improvement.

Running soon became one of the most important things in my life. It was what got me interested in physiology, which eventually led me to become the science writer at Sports Illustrated, and then to start writing science books, which is all just to say that you wouldn’t be reading this book extract if I hadn’t destroyed my right arm in eighth grade.

Back when that arm was a useless weight strapped to my body, I felt like my life was ruined. In the end, though, it gave me a new tool (mnemonics) that would last a lifetime, and rather than curtailing my athletic career, as I feared at the time, it actually extended it. In short, my life changed - improved in the long term - thanks to a constraint.

I was curious to learn more about how and why constraints can be useful because some of the most formative experiences of my life have revolved around them. That’s what my book Inside the Box: how constraints make us better is about.

In researching and writing it, I found out that constraints often have surprising benefits. They can be tools for creativity, collaboration and contentment.

Consider education. Here are four constraints that are relevant to teaching and learning.

1. Limits of working memory

Working memory is the space in your mind where you consciously hold information you want to work with - doing mental math or following directions - and it is very limited.

The cognitive scientist Daniel Willingham, in his book Why Don’t Students Like School?, writes that the “lack of space in working memory is a fundamental bottleneck of human cognition” around which all learning should be designed, but usually isn’t.

Students will be unable to engage in problem‑solving and critical thinking if their working memory is overwhelmed just trying to hold on to new information.

So how can we free up working memory for learning?

To start, get as much information as possible out of working memory. Put as much new information as possible on paper, a whiteboard, a screen, a chart or any place where a learner can refer to it but doesn’t have to hold it in their mind while trying to analyse it.

And second, recognise the benefits of familiarity. If students are asked to analyse a passage of text, but the content is all unfamiliar, they’re going to expend their working memory trying to keep track of the ideas with little left for deeper thinking.

A study of reading comprehension in middle school students provides a simple example. Both “good” and “poor” readers were tested on their comprehension of a story about a baseball game. The good readers who knew a lot about baseball displayed the best reading comprehension, but the poor readers who knew a lot about baseball had better comprehension than the good readers who didn’t know anything about baseball. Familiarity with baseball had a bigger impact than reading skill.

2. Problem space

The Nobel laureate Herbert Simon - a pioneer of both cognitive psychology and artificial intelligence - spent his career illuminating how humans (and computers) solve problems.

A theme running across his work is the concept of a “problem space”: a metaphorical region that the human brain must navigate through in order to get to some solution. In familiar problems, the space is “well‑structured” - marked with clear roads, so to speak - so one merely needs to follow known routes.

For unfamiliar challenges, or “ill‑structured” problems, the problem space is so vast and uncharted that imposing some structure - deciding where to begin and how to advance - becomes the challenge. The solver has to “cut down” the problem space to manageable size in order to explore productively.

In 1990, for one of his many investigations of how people navigate ill‑structured problems, Simon wanted to see whether math and science students at Carnegie Mellon University could replicate a scientific breakthrough made in the 17th century by German astronomer Johannes Kepler, who discovered that the distance of any planet from the Sun precisely determines the time it takes that planet to orbit the Sun.

Simon gave students the same data that Kepler had used to devise his formula. It was broken into two columns: one for distances, and one for orbital periods. But he didn’t tell the students where the numbers were from; he just asked them to find a formula that determined how the two columns were related. Given Kepler’s data, could they recreate his breakthrough? Most of them could not. But a few did.

The difference was that the successful problem solvers systematically shrunk the problem space. They would guess at the specific relationship between the sets of numbers, test the guess, see that it was wrong, take feedback from the specific way in which it was wrong, and then use that information to narrow down what to try next.

The unsuccessful solvers experimented, too, but it was haphazard. They would try a formula that sprang to mind, and when it didn’t work, move to another in pure trial‑and‑error fashion, without taking any other information from each failure to inform next steps.

Because those solvers did not take a structured approach, they made the same errors repeatedly. The larger point is that when exploration is too free, it becomes difficult to learn anything at all.

3. The protégé effect

In 1869, Siberian-born chemist Dmitri Mendeleev developed one of the most important data visualisations ever rendered: the periodic table.

Thanks to his work, the properties of elements could now be predicted - before anyone documented them through laborious experimentation - simply by referring to their location on the table. It was a leap that would soon touch every industry on Earth.

But when Mendeleev developed the table, he was not groping for a fundamental law of nature. He was simply trying to find an arrangement that would help beginners make sense of chemistry.

During the 1860s, chemical knowledge had been building rapidly, but the subject of chemistry was a pedagogical mess. Early textbooks were typically structured like a dictionary: a list of individual elements with no connection between them.

That is why Mendeleev was experimenting with organisational schemes, to help new students grasp chemistry as something more than a disconnected set of facts.

The periodic table, which hangs in virtually every chemistry classroom in the world, was itself born from the needs of a classroom. Teaching introductory chemistry pushed Mendeleev to think through a pedagogical lens.

Docendo discimus - “by teaching, we learn”. That Latin phrase captures an insight from the Roman philosopher Seneca, one that would be borne out by modern science: just the act of thinking like a teacher can prompt insight.

In studies of reading comprehension and recall, participants perform better when they are led to believe that they will have to teach the material to peers (even if that doesn’t ultimately happen) compared to when they believe they will simply be tested. Those who expect to teach organise material more coherently in their minds. The challenge of having to explain focuses how they learn. The finding of improved learning by prospective teachers is today sometimes called the “protégé effect”.

Mendeleev had to explain chemistry to novices, which defined the challenge for him: structuring material in a logical way.

The challenge was difficult, but at least it was clear. That’s another thing constraints can do: act like a spotlight, showing a problem solver where to focus.

4. Constraints of community

While researching this book, I was told repeatedly about a famous playground study. Teachers were directed to take preschool children to local playgrounds that had no designated boundary, and then to playgrounds that had a clear boundary marked by a fence.

At the no‑boundary playgrounds, the children clustered around their teacher. At the fenced‑in playgrounds, the children felt safe to explore, so they left the teacher and roamed widely.
Clear boundaries liberated them to experiment.

Unfortunately, in following up on the suggestions to check out that study, I concluded that it doesn’t exist.

But there’s an interesting nugget in the phenomenon of this non‑study, which I’ve now seen referenced everywhere from design articles to sermons. I think it was accepted so easily because it feels like an analogy to something that we know is true, not about playgrounds but about ourselves.

The idea of having too much freedom would have seemed absurd to most people throughout history, but in the past two centuries it has become a central preoccupation for many influential thinkers.

In his 2024 book The Anxious Generation, New York University social psychologist Jonathan Haidt examined the steep rise in anxiety, depression and self‑harm among young people that has occurred specifically in some of the richest and freest parts of the world. Haidt (controversially) placed some of the blame on social media and how it has altered childhood development with boundless social comparison, a total lack of social norms, and withdrawal from meaningful relationships in the non-virtual world.

“It’s not healthy for anyone to have access to everything, everywhere, all the time,” Haidt told me.

If the normlessness of virtual life is harmful to development, what, in contrast, is helpful? According to the world’s longest in‑depth study of health and happiness: chores.

The Harvard Study of Adult Development began in 1938 and tracked many of its subjects from adolescence until death. In all, the study collected data until 2024, a total of 86 years. One of the recommendations that has come out of that work is to give children chores from an early age.

“It gives children a sense of community, so you are pitching into the family because your participation matters,” according to Harvard psychiatry professor Robert Waldinger, the final director of the study. “We know concern for others and focus beyond the self are good developmental principles, and that the people who are more self-centred are usually less happy.”

The responsibility of chores, Waldinger said, can help give children a sense of purpose and usefulness, and of being part of a team. A separate study that tracked nearly 10,000 children found that kids who did chores starting in kindergarten had stronger belief in their own competence later on.

For adults, the overwhelming finding of the Harvard study is that strong social ties - to family, to friends, to community - are the best predictors of health, wellbeing and longevity. The obvious commonality between the tips for kids and adults is that they involve obligation to something other than oneself.

The way of haiku

In an innovative act of voluntary restriction, the Japanese writer Matsuo Bashō created a serious art form, haiku, using the three lines that others considered a mere introduction to longer poems.

When I was researching Bashō and haiku for this book, I kept coming across a phrase: “the way of haiku.” I found it confusing at first. I had never heard of a “way” of sonnet, or limerick, or any other type of poetry.

Eventually, I got it. Haiku finds depth in the simple, and creativity in constraints that block the path of least resistance.

Haiku is the simplest example of a helpful constraint I have shared here. If it were merely a poetic form, I would find that only moderately interesting. But it is not a form, it is a way - an attitude. It is a way of being, of eagerly accepting unnecessary obstacles because of where they can lead.

David Epstein is the author of the New York Times bestsellers The Sports Gene and Range. He has previously worked as a science and investigative reporter for ProPublica, and as a senior writer for Sports Illustrated. This article is an edited extract of his book Inside the Box