Estimation and Spatial Visualisation.
Visualising quantity and magnitude:
https://mathisvisual.com/build-flexibility-with-magnitude-of-number/
How might you use gesture and spatial language to help children thinking about this activity? (make sure you pause the video at each task to consider a range of strategies/ discussion). What RN ideas might be involved? (e.g., doubling and halving/ times as many etc).