Lately, Iris, three and a half, had enjoyed explaining that their flat was big. Very big.

Nora thought it was rather sweet until one day, in front of another family, Iris announced:

“Our place is much bigger.”

Nora waited until they were alone to try to explain one of those social rules that seem perfectly obvious when you’re an adult and much less so when you’re three.

You could be pleased with your home. But when visiting someone else, it was better not to compare the two flats by explaining that yours was prettier, bigger or better.

Iris thought about it.

“But can I say their home is lovely?”

Yes. That was fine.

Nora was quite pleased with her explanation.

A few days later, they were visiting some friends for the first time.

As soon as they entered the building, they took the lift. Iris stayed quiet for a few seconds. She looked at the buttons, the mirror and the metal doors.

Then her face lit up.

“Your lift is really lovely!”

The trouble was, their friends weren’t there yet.

They hadn’t even reached their floor.

Iris had simply remembered the rule: when you visit someone, you can say something kind about the place where they live.

And technically, she’d done it perfectly.

Obvious rules often come with invisible small print

When we tell a young child “be polite,” “don’t show off” or “say something kind,” we sometimes feel we’ve given a precise instruction.

But we mentally add all sorts of information the child has never been given.

When to do it. Who to say it to. What to say it about. And above all, in what situation.

Iris hadn’t misunderstood the rule.

She’d understood it exactly as Nora had explained it.

Give an example rather than a whole rule

Nora didn’t need to explain every subtlety of social life before each visit.

But she could make some instructions more concrete.

“If you think something in their home is lovely, you can tell them.”

“And we wait until we’re with them to give them the compliment.”

What had seemed like a lesson in manners had turned into something else: a reminder that children don’t always guess the parts of a rule adults leave unsaid.

And since then, Nora has been a little more wary of instructions that begin with “it’s simple.”

Especially in lifts.