Motion sensors and measures

Didactically, there is no need to introduce acceleration or velocity as be a derived quantity, whatever the status as an SI unit, or the desired final definition. Tools to measure acceleration more or less directly are widely available, and not so expensive, even if the ability to represent it as a vector is often missed. (There is a gap in the market for a good Doppler effect based velocity measuring tool). Alternatively, at a larger scale, that GPS technology is widely embedded now presents many possibilities for representing the quantities, in didactically appropriate ways. Melding such sensors effectively to computational power and portable high-resolution screens offers genuine choices about how to present the data. Dials, gauges, data tables and cartesian graphs may be comfortingly familiar to those inducted into physics when the current representational flexibility was not available, but it does not follow that this is the best or only pedagogic path. I think we could make more of vectors, particularly in teaching about kinematics.