Taking a point of view

An essential step

'Taking a point of view' is neither more nor less than establishing a frame of reference. Still, it is perhaps a more accessible formulation as a starting point (for development of the idea see, for example, the web resources for Supporting Physics Teaching). It is essential, but often not explicit, to take a point of view in order to record a velocity or a displacement. Starting with "what Charlie notices" or "what Alice records", rather than with somewhat formal arrays of measuring rods and clocks is a better way to make it more likely that this essential step of taking a point of view and incorporating that into the records of motion will become more widespread. Such an approach can make an approach to relative velocities, which often appears as a later, somewhat optional complication in current curricula, appear both more natural and more essential. You can start somewhat informally by exploring what Charlie or Alice (in an example where this pair are not co-moving) notice, then what they record, and how that move to formalisation can be handled by either character. Perhaps, if you wanted to lay the real foundations for thinking about relativity, you'd compare what they do and do not agree on in describing precisely the same process.

This actor, or observer-based, approach also aligns well with the stories-of-journeys strategy promoted in the discussion about starting with two dimensions.