In this lesson, the fundamental principle of the lever, as described by the mathematician Archimedes, is explored. Using everyday examples like a playground seesaw, the lesson details how levers work by balancing effort and resistance forces around a fulcrum, illustrating the concept with real-life applications. The lecture emphasizes the power of simple machines, showing how levers can significantly reduce the force needed to move heavy objects, and ends with an exploration of the theoretical capabilities of levers.