Before a football game, the captains of each team come together in the center of the field with the referee to decide which team will receive the ball first. They decide this by flipping a coin in the air. One of the captains calls "heads" or "tails." When the coin lands, either heads or tails will be facing up. If the player called the coin toss correctly, his team gets the choice of whether to receive the ball first. If not, the other team decides. A coin toss before a game involves what we call probability.
Probability is a measure of how likely it is for an event to happen. It is measured as a fraction between 0 and 1. If a particular event is certain not to happen, then the probability is 0. If the event is certain to happen, then the probability is 1. In between these two extremes are a wide variety of probabilities (expressed as fractions) that the event will or will not happen.
