Why can a child read numbers but make place-value or comparison errors?
Reading may be memorised without understanding each place. Use place-value charts, partitioning and number lines, connecting decimals to money and measurement to give the separator meaning.
Practical takeaways
- A digit’s value depends on its place.
- Zero holds a place and serves a purpose.
- Compare from the highest place and add trailing decimal zeros when needed.
Place-value charts and partitioning
Place each digit in its column and read in groups. Partitioning 406 035 reveals zero’s role better than fast reading.
Comparison and rounding
Compare from the left until the first difference. To round, identify the target place and the next digit, connecting the result to a realistic estimate.
Meaning of the decimal part
Use dirhams and centimes or metres and centimetres to explain tenths and hundredths. 4,5 means four and a half, not 45.
Decimal-separator errors
For comparison, write 3,5 as 3,50 and compare tenths and hundredths. In addition and subtraction, align decimal separators to align place values.
Frequently asked questions
Is 3,45 greater than 3,5?
No: 3,5 = 3,50, and 3,50 is greater than 3,45.
What does zero do inside a number?
It preserves place positions; removing a zero from 406 035 changes the number completely.
When do we use rounding?
To estimate, check reasonableness or give an approximate value when requested.