All in a jumble

This interactive gives students a range of objects to match with the appropriate metric unit and approximate size. Students may need to use estimation skills (or research) to determine the size of some objects. Students can submit their responses, find out which are correct and then amend their incorrect responses. The puzzle resets with some different questions each time you reload it. There are also three downloadable worksheets to use offline. Note: this is a UK-based website so some references are UK-specific.