What are some measurement units that would be useful in describing a basketball court, the length of a river, and the length of a grasshopper?
This question is all about matching up units that are appropriate to what is being measured. As a quick example, if we were to talk about the distance between the Sun and Earth, we usually talk in terms of miles or kilometres. It would be less helpful to talk about that distance in terms of micrometres (which is a unit that is suited to measuring hair width) or lightyears (the distance between the Sun and Earth can be expressed in light-minutes!)
A basketball court could be expressed in metres, feet, or perhaps even yards:
A river could be expressed in kilometres or miles:
and the length of a grasshopper could be expressed in terms of centimetres, millimetres, or inches: