see-saw (n.) Look up see-saw at Dictionary.com
also seesaw, 1630s, in see-saw-sacke a downe (like a Sawyer), words in a rhythmic jingle used by children and repetitive motion workers, probably imitative of the rhythmic back-and-forth motion of sawyers working a two-man saw over wood or stone (see saw. Ha ha.). Reference to a game of going up and down on a balanced plank is recorded from 1704; figurative sense is from 1714. Applied from 1824 to the plank arranged for the game.
see-saw (v.) Look up see-saw at Dictionary.com
also seesaw, "move up and down," 1712, from see-saw (n.). Related: See-sawed; see-sawing.