Recording and generating journeys

Step 2

In the school laboratory this could be coupled with strobed long exposure images of polished steel ball bearing: records of natural motions on different sculpted surfaces. Or put a suitably mounted flasher to work in similar environments. (Such a flasher can be rather cheaply fettled using a flashing bicycling light as a starting point).

This line of development could be technologically supported by using toy robots that can be programmed to traverse two-dimensional paths. Introduce challenges to explore or reinforce an understanding of sequences of track segments, beginning to formalise the idea of a motion as a sequence of track segments. I'd suggest restricting these to robots that traverse a plane, as two dimensions are pedagogically optimal. On the screen, sequences of displacements could render a track visible, track segment by track segment. Or you could simply draw on a map: idealising as you go, by restricting the track segments to straight lines(so mimicking the light streaks which appear in the long-exposure photographs as a result of fast-moving objects). You are providing a low-resistance route to predicting or retrodicting journeys as a sequence of arrows.

On paper, now is the time to introduce motion diagrams, with the separation of the images or dots representing a track segment. I'd suggest moving from qualitative to semi-quantitative and then quantitative interpretations often, to encourage physical understanding.

The first formalisation is a plan view of a motion diagram which is intrinsically two-dimensional and composed of a sequence of track segments. Again it might be useful to make strong links with past experiences, connecting this representation with the descriptions of journeys as sketch maps, so a third-person point of view, and with reports of such journeys from the first-person point of view.

From these formal diagrams draw out the idea of taking a point of view and recording when something was where, so relating a sequence of displacements to the motion diagram. This sequence of displacements can then be simply represented by a sequence of stylised arrows, from the chosen point of view.