This prompt can be used in many ways… below is some very messy boardwork from a lesson. I have listed out the actions from the lesson below. The focus of this lesson was not on memorising conversion rules, but in getting a sense of the contentedness of the units of measurements, primarily via developing a sense of proportionality. 1km = 1000m, so 2km = 2000m etc.
Possible Sequence of tasks
1. Write down 1km = 1000m, 1m = 100cm and 1cm = 10mm
2. Ask pupils to label the top line using metres
3. Select some in between values such as 8.5km, 0.3km and ask pupils to write them in metres.
4. Go through a similar process of metres, asking learners to convert each of them into cm. Select some in between values for conversion to cm.
5. And the same again for centimetres into millimetres.
6. Now go back up the way and look at, for instance 9m. We’d previously written it is equal to 900cm. Convert this answer to mm. Ask pupils to do the same for some other places on the metre line.
7. Look at, for instance 7km. We’d previously written it as 7000m. Convert this to cm and mm. Ask pupils to do the same for some other places on the km line.
credit: @chrismcgrane84
Starting Points Maths 
