The why phase: when it starts, how long it lasts, and what to say when you run out of answers
It is ten past seven. You have explained why it gets dark, why the neighbour’s dog barks, and why socks come in twos. Then comes the next one: “But why is the Moon following us?”
If that is your evening, this page is for you. We make Pukki, an app that answers children’s questions out loud, so we have spent a long time reading what researchers know about “why”. We are not writing as parents. This is what one study found, and what seems to help.
On this page: Why they ask again · Four kinds of why · When you don’t know · The ones that are yours · One answer, three ages
The short version
- It is normal, and it changes. The all-day stream belongs to the preschool years. Later the questions get more specific.
- A repeated “why” often means the last reply was not an answer. One true sentence usually moves things on.
- “I don’t know” is fine when something comes after it: “What do you think?” or “Let’s find out.”
- Some questions are yours. Birth, death and belief are best answered by you, in a short true sentence.
When it starts, and when it eases
Parents usually meet it in the preschool years, once a child has the words “why” and “how”. The children in the study below were between two and five.
Later the questions get more specific, and more of them go to teachers, friends and books. The all-day stream passes. The curiosity underneath it is the part you probably want to keep.
Why they ask the same thing again
In 2009, three psychologists looked at what small children do after they ask “why”. They read transcripts of everyday talk at home, and then ran a test with 42 children aged three to five. When an adult gave a real explanation, the children tended to agree or ask a new question. When the adult said something that was not an explanation, the children tended to ask the same thing again, or to offer an answer of their own.
So a repeated “why” can mean the last reply did not feel like an answer. “Because it just does” brings the question straight back. One true sentence often moves things on.
Four kinds of why
They are not all the same question, and they do not all want the same thing.
- How does it work? “Why is the sky blue?” wants a fact. Short and true is enough.
- Why is that the rule? “Why do I have to brush my teeth?” wants a reason. Give the real one.
- A worry in disguise. “Why do people get old?” is sometimes about the science and sometimes about Grandma. If you are not sure which, ask: “What made you think of that?”
- Stay with me. The why at lights-out is often about you, and a few more minutes. You can say so kindly: “That’s a good one for breakfast. I’ll remember it.”
What to say when you don’t know
“I don’t know” is a complete answer when something comes after it.
I don’t know. What do you think?
Their guess is often worth hearing, and it buys you a moment.
I don’t know. Let’s find out.
Then look it up together, with them watching how you do it.
I don’t know yet. Let’s write it down.
A list of questions on the fridge is a good thing to own.
You do not need to be right on the spot. Taking the question seriously is most of the answer.
The ones that are yours
Some questions have no encyclopedia answer: where babies come from, what happens when someone dies, what your family believes. A short, true sentence from you is worth more here than anything a book or an app can say, because the answer carries your family’s way of seeing things.
One question, three ages
Here is how the same answer changes with the child. These are answers Pukki gave when we asked it ourselves, once for each age.
For a 3- or 4-year-old
The sky looks blue because sunlight spreads through the air. Blue light spreads more than the other colors, so blue fills the sky.
For a 5- or 6-year-old
The sky looks blue because sunlight gets scattered by tiny bits of air. Blue light scatters more than the other colors, so blue comes from every part of the sky.
For a 7- or 8-year-old
The sky looks blue because sunlight bumps into tiny bits of air. Blue light gets scattered across the sky more than most other colors, so blue reaches your eyes from every direction.
The fact stays the same. What changes is how many ideas the sentence asks the child to hold. All five ages, and what we read the answers against, are on Why is the sky blue?
More, by age: Why does the Moon change shape? · Where does rain come from? · How do planes stay up in the sky? · What is lightning? · Where do dreams come from?
Tonight
Pick one question your child asked today. At dinner, ask it back: “You asked why the Moon follows us. What do you think now?”
Then listen to what they say.
Where Pukki fits
Pukki answers the how-does-it-work kind of why, out loud, in words made for your child’s age. Some questions it hands back to you. Its answers are written by AI and can be wrong. More on What is Pukki?
Sources
- Frazier, B. N., Gelman, S. A., and Wellman, H. M. (2009). Preschoolers’ search for explanatory information within adult–child conversation. Child Development, 80(6), 1592–1611. Read the paper. Read on 13 October 2026.
- The sky answers were read against NASA Space Place: Why Is the Sky Blue?