seesaw

thumb|250px|Seesaw in 1792 painting by Francisco de Goya thumb|250px|A set of conjoined playground seesaws

A see saw (also sometimes known as a teeter-totter in North America) is a long, narrow board supported by a single pivot point, most commonly located at the midpoint between both ends; as one end goes up, the other goes down. These are most commonly found at parks and school playgrounds.