As designers we often have to present our work, whether through presentation boards, renderings or physical models. The highest achievement of this art form is if you can express a complicated concept that the viewer can grasp in seconds—and it's even better if you can do it wordlessly, eliminating any language barrier.
This simple demonstration put on by U-Haul at the recent Commercial Vehicle Safety Alliance Conference might be the best-designed presentation we've ever seen. Their task was to demonstrate how the weight distribution on a loaded trailer affects driving dynamics. To do it, they used an RC Ford Mustang running on a treadmill:
The principle is easy to grasp and provides more data than, say, having a bystander witness an actual trailer crash: