This article proposes an evidence-based and engaging approach to teaching the mechanisms driving the movement of tectonic plates that should lead high school students towards the prevalent theories used in peer-reviewed science journals and taught in universities. The methods presented replace the inaccurate and outdated focus on mantle convection as the driving mechanism for plate motion. Students first examine the relationship between the percentages of plate boundary types of the 14 largest plates with their GPS-determined plate speeds to then evaluate the three possible driving mechanisms: mantle convection, ridge push and slab pull. A classroom experiment measuring the densities of igneous and metamorphic rocks associated with subduction zones then provides a plausible explanation for slab pull as the dominant driving mechanism. Basalt and gabbro of oceanic lithosphere, that is positively buoyant compared to the peridotite of the asthenosphere, changes to denser negatively buoyant eclogite as it descends so that it sinks into the mantle and pulls the tectonic plate along behind it.