In order to answer a question you have to be able to say the answer. Sometimes when helping our children learn something new, like fractions, we may forget that not only is the idea new to them but so are the words. Children need to become familiar with these new words in order to answer questions.
It takes time to become accustomed and familiar with new words and phrases. It would be nice if people could be told something once, then be able to recall and use this information perfectly forever more. But it doesn’t often happen.
The names of fractions in English are somewhat irregular, at least to start with because English, as it developed, absorbed words from more than one other language (usually Anglo Saxon or Old English and Latin).
For example half and third are derived from the Old English words ‘healf’ and ‘pridda’. But quarter comes from the Latin ‘quartus’. Next comes fifth, not ‘fiveth’, which comes from the Old English ‘fifta’. After this, things settle down with sixth seventh and so on. But it is still necessary to learn the exceptions.
Another common difficulty is saying remainders and improper fractions. For example five divided by four is one remainder one or one and one quarter. It is very common for children to be confused at the two ones in one remainder one and in one and one quarter. After all these are not phrases that they are likely to have used before. In contrast by the time children learn to count at school they are likely to have used the words one, two and three many times. (How many ice creams would you like?). But one and one quarter is more of a tongue twister.
Another difficulty comes with converting kilograms to grams, or kilometers to meters. This is often thought of as a math problem. But it is in largely a speaking problem. There are two parts.
Firstly just repeat exactly what is said but replace kilo with thousand and thousand with kilo.
So two kilograms becomes two thousand kilo grams.
And three thousand grams becomes three kilo grams.
It really is that simple!
Secondly, learn the how to say fractions of a thousand. So 1/2 a kilogram is five hundred grams which means five hundred grams is half a kilogram.
Children seem to be comfortable with saying two thousand five hundred grams for 2 1/2 kg and three thousand five hundred grams for 3 1/2 kg.
But ten thousand five hundred grams for 10 1/2kg
or one hundred thousand five hundred grams for 100 1/2kg
seem to be more difficult to say, until they become familiar.
For some reason it seems that saying one thousand five hundred grams for 1 1/2 kg is takes longer to become familiar with.
By the time they are comfortable with saying and one hundred and one thousand five hundred grams for 101 1/2 kilograms you can be confident that they have got to grips with this particular type of problem.