A simple activity that focuses on estimation and measurement of length.
Students were placed in mixed ability groups and each group was given the above worksheet. We ran this activity like a competition between groups. I had a big timer on the interactive whiteboard and when I said "go", each group had three minutes to come up with as many items that would measure to approximately 1cm. We repeated this for 10cm, 50cm, and 100cm/1m.
Once again, I found this activity from NZ Maths and modified it for my maths class.