I'm a big fan of sticking to definitions, but they normally need to be presented in sets to the uninitiated, or they become confusing.
IE: if you decide to put forward an example sampled across 6.6 seconds resulting in the case of no velocity despite much distance covered, the concept of discrete units and sampling intervals might need mentioning. It's probably easier to go Lagrangian, and assume the 1fps sampling unit, and examplify on that, if you don't want to touch on calculus (which I find tends to be more intimidating than most other fundamentals for new comers).
