DD Year 3 numerary metres/centimetres/km help!!

[ClareL]

My DD has just bought her homework home for numeracy converting metres to cms and km to metres. Easy questions ie. 100cms = (answer) 1 metre. But there are also question 5 1/2 metres = ? centimetres. I have had 100 coins on the tables trying to explain quarters, halves, 3 quarters etc. but she couldn't get it into her head. I've drawn diagrams of circles drawing segments etc. Anyone have any good ideas that can make it easier. What else could I use rather than coins.

does she know that 2 50p's are £1? Maybe go about it that way rather than 100 coins.

A number line from 1 to 100 (doesn't need to have every number on it, maybe just 10, 20, 30 etc) demonstrating 50 exactly in the middle?

This site is good for practising, and for visual aids to understanding measures. Try pages 3 & 4 for fractions of a metre.

We used the number line for a lot of the questions but when it come to the questions where whats half of 500 kms. Number line only went up to 100.
I sometimes think that the homework they bring home is for me to teach my child rather than it being taught in school. She said they had only just started doing these sort of questions but I can't see why I should have to sit for hours with my child trying to get her to understand this sort of thing. I am quite happy to put the time and effort in but surely homework should be to instill the workings out into the child rather than it being taught at home!! Do I sound mean??