Introduction
In this interview, Caitlin reads the decimal parts of numbers as if they were whole numbers. This is sometimes a sign of whole number thinking. When she explains the meaning of the number 4.26, she explains the 26 as 2 tens and 6 ones, although she knows there is something more that she doesn't understand.

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

Interviewer:
Could you please read out the numbers on these cards?

Caitlin:
Oh point 4

Zero point 4 is preferable.
Many teachers encourage beginners to read this as four tenths.

Caitlin:
nine point seven

Correct. Many teachers prefer nine and seven tenths.

Caitlin:
Oh point one hundred and sixty three

Incorrect. Should be zero point one six three to emphasise the difference from whole numbers.

Caitlin:
Oh point twenty five

Incorrect. Should be zero point zero two five. Caitlin probably thinks 0.025 and 0.25 are the same.

Caitlin:
Oh point ninety seven

Reading decimals like this gives teachers a clue that the student may have little idea about the meaning of the decimal part.

Caitlin:
Four point twenty six

Incorrect. Should be four point two six.

Interviewer:
If a friend asked you to explain what this last number means, what could you say to help them?

Caitlin:
Well the 4 means 4 wholes and then there are some extra bits but they don't make another whole.

Interviewer:
Could you explain more about the extra bits?

Caitlin:
There are twenty six of them.

Interviewer:
Has your teacher talked about names for the different columns?

Caitlin:
I think that maybe is the tens and...

Caitlin:
...that is the units but sometimes you can call them other names too...but I get confused about the other names.

Caitlin sees the 26 as 2 tens and 6 ones although she knows there is something more that she doesn't understand.