The Lower School engineering teacher was designing a lesson for her first graders with the help of a Middle School student. How to lead her young students to discover the principle of the lever?
As Wikipedia so aptly put it, "Levers can be used to exert a large force over a small distance at one end by exerting only a small force over a greater distance at the other."
The problem here is how can a lighter student raise the mass of the (somewhat) heavier adult? Through trial and error the student discovered that moving the board so that the greater length was on her side would exert the force required to lift the adult. As Archimedes said, in another moment of discovery, "Eureka!"
