They know the column names are similar, but assume they are the same. This can be because the child has not got even a basic understanding of the meaning of fractions, or often because of hearing and language difficulties . As noted above, the place value names are, to an extent, symmetric around the ones column. This seems to remind some older students of the way in which the positive and negative parts of the number line are symmetric about zero. This may dispose some of them to interpret decimals as negative numbers .
Some children are confused about whether the first column after the decimal point is tens or tenths.
These children may be good at money and may also have had a lot of practice with two decimal place numbers. They may be good at interpreting 4.8 dollars as 4 dollars and 80 cents and 4.63 dollars as 4 dollars and sixty three cents. Veronica in Grade 5, for example, seemed to routinely think about this. Some children are only familiar with tenths and some are only familiar with tenths and hundredths. They know nothing about the names or values of other place value columns.