Why being smarter sometimes makes our explanations dumber

Slow down.

I have been told approximately two million times in my life to slow down. I have been told I do too many things (true, and not healthy). I talk too fast (I have so much to say!) I jump to too many conclusions in my writing, failing to bring the reader along with me (which pains me because I truly value effective communication).

Which is why I was so struck by a recent newsletter about how being smart about something can makes us worse at explaining things, by Peps McRea, an inspired British educator and the author of Evidence Snacks, a “five-minute weekly email for research-hungry educators.”

Peps explains complex research in digestible, actionable ways, like this:

“As teachers, we are at constant risk of ‘expert-induced blindness’ (or ‘curse of knowledge’). This is a cognitive bias which makes it hard for us to set aside what we know and empathise with those who don’t. Answers come so easily to us—it’s hard to imagine anything otherwise.”

The research he cites shows that learning new information can negatively affect our ability to judge what others know. The more we know the harder it is to remember not knowing.

I am very guilty of this as a parent. I will see a concept like compound interest or the importance of a free press, and assume my children will understand with cursory explanations why they matter. This is nuts. My kids don’t have any of the background knowledge that makes all this so clear to me (15 years as a financial journalist, 35 years of managing my own money, a quarter of a century working as a member of a free press).

Take compound interest. Here’s how I have tried to explain it. “If you start to save early, compound interest means your money grows exponentially over time. You will have more money later. So save, starting now.”

To me, this makes perfect sense. I understand how interest accumulates, how percentages work, and why time is a crucial factor in wealth-building. My first beat in finance was the retirement market, and I recall seeing charts that showed compound interest, interviewing the heavyweights of retirement at Vanguard and Fidelity, and immediately opening my 401k because it was clear to me whatever crumbs I could afford to save at 25 would be rewarded over time.

To a teen who hasn't yet grasped exponential growth—or the way stock markets work—this explanation might seem vague and unconvincing.

A good teacher (or parent) would need to assume little or no prior knowledge; break it down; explain it clearly; and check for understanding along the way. That might mean making sure they understand exactly what a percentage is before you even begin. Then explaining simple interest using examples; then compound interest; and finally, perhaps reinforcing the message with some impressive stats or examples.

Suze Orman explained to Mika Brzezinski on Morning Joe that not buying a Starbucks every day (when Starbuck cost $3) and investing that $100 a month in a Roth IRA retirement account from age 25 to 65 would make you a millionaire.

Peps’ email talks about how hard it is even for teachers to get into a beginner’s brain. The more we know, the further we get from remembering what it is to be a novice, and how uncomfortable it can be to not understand something.

The curse of being an expert shows up in using jargon or technical terms (like compound interest, or totalitarian regime.) We underestimate how messy and slow learning can be because we are experts. When talking to our kids about complex ideas — even ones that seem simple to us — we need to slow down. We need to not give them the answers, because stumbling their way towards it is where learning happens.

I particularly love Peps’ last point: “We assume that students appreciate the value of what we’re teaching them, or why we’re doing it this way.”

Guilty again! If I am taking the time to explain something, I assume my kids know it's important and I assume they will give me their attention. I’m usually wrong on both. Peps advises teachers to assume less, assess more. In a class that means finding ways to see where kids are. This can be hard because teens in particular are wary to admit they don’t know something and look bad in front of their peers. Tech can be useful here: an anonymous poll on a device is a great way to check understanding.

For parents, it’s easier. We just need to remember when checking for understanding to not sound judgemental. We might say: “This stuff is crazy complicated and I wonder if I am explaining it well?” rather than: “This is clear, right?”

Sometimes our own explanations won’t be welcome, or good enough, and we might need to look for alternatives: GenAI, YouTube, siblings or grandparents on FaceTime.

This week, my older daughter was trying to explain to my younger one how John Dalton’s Billiard model of atomic matter made way for JJ Thompson’s plum pudding model. She understood it well but struggled to explain it. I suggested we try to find a video on the internet, which did the trick.

No one is an expert on everything, of course, and there’s probably plenty that our teens will learn that we won’t understand ourselves. At those times, it’s helpful to fumble towards an answer together, modelling curiosity and perseverance in the face of feeling dumb. But when we do know the answers to something, it still pays to slow down. Don’t let the things you know get in the way of explaining them clearly.

PS. In case you want the compound interest example:

Start with simple interest

If you put $100 in a bank with a 5% interest rate, after one year, you earn $5. That’s simple interest—just earning on the original amount.

Offer an example: “If you keep it for 10 years and never touch it, you’d have $150—your original $100 plus $50 in interest.”

Introduce the magic of compounding

There’s another twist! With compound interest, you don’t just earn interest on the original amount—you earn interest on the interest too.

Build on the example: “After the first year, you have $105. In the second year, instead of earning just $5 again, you earn 5% of $105—so now you have $110.25. The extra $0.25 might seem small, but over time, it adds up like crazy.

Reinforce the time element

Starting early matters a lot.

If you invest $1,000 at age 15 and never add another cent, at a 7% interest rate, by the time you’re 65, you’ll have over $32,000. But if you wait until age 30 to invest the same $1,000, you’ll only have $7,600 by 65.