Introduction
This interview is based on the game "Hidden Numbers". Courtney begins by choosing shorter decimals as larger but after a wrong guess, she looks for zeros after the decimal point. Confusing decimals with fractions, she wants to know how many parts a quantity will be divided into.

Comments: Text in italics
Interviewer: Text in red
Courtney: Text other colour

Interviewer:
In this game, you have two mystery numbers and try to guess which is larger.

Interviewer:
See the decimal point in both numbers?

Courtney:
Yes, I guess I'd better look at the whole number part first...

Almost all children know to compare the units first.

Courtney:
So that's a three...

Courtney:
and that's a three too...So I think the top number is bigger because it's shorter.

Courtney chooses the top number, expecting that as there are fewer pieces, they must be larger.

Her choice was wrong

Courtney:
ohhhh...

Interviewer:
Let's try again

Courtney:
OK...I'll just check the first numbers..

Courtney:
So I think it will be the top number, but I'll just check this door...

This time Courtney is more cautious.

Courtney is now comparing a 2-digit whole number with a 3-digit whole number.

Courtney:
Ummm... it's still probably the top number but I'll just check here..

Courtney:
So there are 3 hundred and something pieces in the bottom number and they would be really small, so I'll choose the top number...

Courtney has been lucky

Courtney:
Great!!!

Interviewer:
Try another one?

Courtney:
Yes

Courtney:
I'll open these whole number doors again to check...

Courtney:
I think it's the top number again, but I'll have to check for zeros after the point.

Courtney:
Umm..and open this door...

Courtney:
This really is a tricky one...I still can't tell... I guess I'll need to open this door...

Courtney is now comparing two 2-digit whole numbers.

Courtney:
...and this door...

Courtney:
I still can't tell! This one is a hard one...I'll open this door next.

Courtney:
Well 2 isn't very big so it's probably the top number again...

Interviewer:
Are you sure about that or do you need to open the last door?

Courtney:
I guess I still need to check it.

Courtney:
They're the same!! That was a trick question!!

Courtney sees both of these as 7 with something divided into 32 parts.