A seesaw is a board which is balanced on a fulcrum. When two people sit at either end of a seesaw, they can use their respective weights to move their ends of the board up and down, causing the person on the other end of the board to move. Seesaws commonly appear in playgrounds, because they are popular children's toys, and sometimes adults indulge in a bit of seesawing as well, because it can be deeply enjoyable when the two users reach a rhythm.
There are a variety of regional names for the seesaw, including teeter-totter, tilting board, dandle board, and teedle board. In all cases, the basic mechanics of the seesaw are the same, and because seesaws are simple and easy to understand, they are often used as examples of levers in science classes. Especially in the early stages of learning about physics, seesaws crop up quite frequently in word problems.
While seesaws are used most frequently as toys, they have some practical uses as well. For example, a seesaw can be connected to a turbine, using the energy of the movement to generate electricity. Seesaws can also be attached to pumping mechanisms for water. In some rural communities, seesaws are often used for these purposes, allowing the play of children to generate a positive benefit for the community in general.
There are some dangers to using a seesaw. A sudden shift of weight or abrupt dismount on one end of the seesaw can cause the person on the other side to fly off, sometimes to comic effect, and sometimes at great risk of injury. Because injuries are a concern, many seesaws are situated in areas with padding, so that when someone falls off, he or she will not be severely injured. Children are also commonly warned to be careful when using a seesaw.
Seesaws are also used in acrobatics. The same flying dismount which can be dangerous for children can be useful for an acrobat, who may seesaw with a partner to achieve more momentum for flips and other feats. In this sense, a seesaw is almost like a springboard, and when used by trained acrobats, it is possible to do a range of tricks on a seesaw which can be quite visually interesting.