We use our ruler to measure things. Our ruler has numbers that show us how big something is. The ruler that you have shows measurements in centimetres (cm).
When we have to measure things that are bigger, then we use a metre ruler like the one that I showed you in class. With this we measure in metres (m). We do not use this often but when soemthing like a door is too bug to measure with the ruler in our pocket, then we have to use the metre ruler!
Remember: 1m = 100cm
Then there are times when we have to measure very big things like a road. Here we use kilometres (km).
Remember: 1km = 1000m
Now, soemtimes we are asked to change metres in centimetres or the other way round. What do we do? Take a look at the following examples:
If we have to change 130cm in mentres... 130cm = 1m 30cm ... The 130 were friends but then they faught and tried to stay away from each other!
If it is the other way round... 1m 30cm = 230cm... Numbers that fight, end up making friends again and so they are joined together!
The same works with km ... 5km 400m = 5400m and the other way round 5400m = 5km 400m