Scales can be used to show large amounts. When the numbers get too cramped, the scales are often simplified and a label is used to show the value of the numbers used on the scale. Scales are a bit like number lines. On a measuring jug, the scale goes upwards rather than across. It is read up from the bottom. On weighing scales, there may be a circular scale, an arrow rotates clockwise and the numbers may be displayed around the edge. While this scale goes in a circle, it is really just another type of number line.
Set the classroom out prior to watching this clip with scales and weights, coloured water and measuring jugs and a table with paper scale number lines. Watch the clip in full and then challenge groups of children to move around the classroom filling the measuring jugs, weighing classroom objects and identifying the correct numbers on paper scales. All adults in the class should reinforce the correct terms such as ml, grams and so on.