Benjamin Franklin is probably most famous for flying a kite with a metal key attached to the bottom through some storm clouds. Without the science, that actually makes him just sound a bit simple. So here's what he was doing: He was trying to see whether he could pick up an electrical charge - thus proving some of his theories about electricity (namely that lightning was electricity, which might seem obvious now but which hadn't been proven at the time). The experiment was successful - the kite picked up a charge that caused visible sparks when a person touched the key.