Athletic sports encompass a wide range of physical activities, including running, leaping, and throwing. A dancing competition might be structured as a physical game, with victors and losers. Physical activities include treasure hunts and other games that involve movement. Games played for fun but also intended to teach someone how to play chess or checkers are called "games for instruction." Games can be played by one person or several people. Individual games usually have names such as "marbles," "backgammon," "rock-paper-scissors." Team games may be named after the number of players involved ("nine innings"), after important events in the game ("first base is first base because it's the first thing you hit if you're playing baseball") or for no apparent reason at all. In many team games, each player takes a turn being the "it" player on the field; in others, they may have special roles such as pitcher or catcher. Game types which may involve more than one game in one event include championships and contests. A championship game is played to determine who is champion; a contest is played until one side achieves a predetermined goal (e.g., "first to five wins"). All forms of athletics involve some type of game - whether it is played for fun or for reward. When an athlete plays against himself or herself, it is called "somersaulting".