Why do this problem?
gives pupils the opportunity to find ways of measuring friends' heights, trying to avoid difficulties. The questions also encourage them to think about the units they are using.
Talk to the children about measuring heights of people, to find out what experiences they have had. Lead them then to consider the two pictures and the difficulties that the boy and girl are having. Discuss these difficulties and encourage them to offer suggestions as to how they think they could do it more accurately.
Give learners the opportunity to try out their own ideas and after a suitable length of time, bring everyone together to share their methods.
If it has not come up naturally, you could then lead the group in a discussion about the units they have used and challenge them to convert centimetres to metres and vice versa.
How did you do the measuring?
What is that measurement in metres and centimetres? How do you know?
Have available as many different pieces of measuring equipment that you can to try and pre-empt the children's methods. Do try to accommodate any unusual requests!