The ideas of time, space and motion may be inextricably tangled: to notice and record the passage of time you need a clock, which will involve regular changes over time, and these are otherwise known as motions. Any approach should respect this potential difficulty, and not use any representations that might conflate duration and distance, for example.
Any representational path may impede learning or may be helpful in developing the idea. The facility of the path will be connected to the way children can reason with the representations employed.
Current practice commits to a selection of operationalised and customary measures and definitions, which are strongly linked to 'teacher rituals'. These are rather formal, complex and forbidding, and current practice does not seem to focus on providing tools for thought.
Using scatter or line graphs as the primary representation in motion, often as a time series, causes didactical and pedagogic difficulties due to unavoidable reduction to one dimension. As a result, at best you're dealing with signed quantities, and teacher talk often seems rather knotty (e.g. 'one-dimensional vectors' seems not to be a straightforward way to introduce the idea of a vector), as the resources to hand do not seem to easily support the kinds of distinctions they want to make.