If you haven’t seen this “Cosmic Connections” video by the incomparable Lawrence Krauss, you ought to:
There’s enough fantastic connections between us and the cosmos to watch the whole lecture more than a few times but at the 38 minute mark he explains the incredible connection of both Special and General Relativity to the GPS technology you hold in your hand. Every one on the planet should know this and could easily understand the profound implications and daily use and need of such “esoteric” theory as that of Einstein’s greatest contributions to our understanding of the world.
When I get to be Komissar of Education, every high school student will learn this. Any kid that can master the intricacies World of Warcraft can understand Relativity Theory!
And if that’s not enough, consider this more earthly connection to the phenomenal technology of GPS: Continental Drift.
We know the continents moved apart from all sorts of evidence accumulated mostly in the last 50 years or so, since we could dive to the mid-ocean trenches, accurately date the seafloor, better understand vulcanism (Wiki: Continental Drift or Plate Tectonics for the incredible details) and match up the geology and fossils of the continents, such as the eastern coast of South America and the west coast of Africa to an even finer degree.
And now these two continents continued separation of roughly 3cm per year is confirmed by the same GPS system you use to get to your Uncle’s new house at Christmas time: