Teeter or teeterboard is used more generally in the northeast United States, while teeter-totter, probably the most common term after seesaw, is used across the inland northern states and westward to the West Coast.
(Teeter Tunnel in Maocao)
How does a teeter totter work (what’s the working principle of a teeter totter)?
Teeter totters working principle: to generate fun with two kids on either end. When Child A sits on an end and pushes with their feet against the ground, it causes the other end of the board to move in an equal and opposite direction. This sends Child B at the other end down towards the ground. and it bring happiness by repeated interactive movement.