Concept:The child misunderstands decimal place value by treating decimal parts like whole numbers.
They incorrectly think that more digits after the decimal always mean a larger number.
Explanation:The child compares
4.78 and
4.9 by looking only at the digits after the decimal point.
They see
78 (two digits) and
9 (one digit) and assume
78>9 because of the whole number rule.
Similarly, for
7.26 and
7.3, they see
26 as larger than
3 because
26 has more digits.
This is a common misconception: over-generalizing that a three-digit number is greater than a two-digit number.
The child ignores the true value of decimal places — tenths, hundredths, etc.
In reality,
4.9 (which is
4.90) is greater than
4.78, because
9 tenths is greater than
7 tenths.
The error is not due to carelessness, lack of practice, or a learning disability.
It is a clear case of applying a whole-number rule incorrectly to decimal numbers.
Answer:Option C: has over-generalized the rule that a three-digit number is greater than a two-digit number