Dominoes are small plastic or clay tiles with a number of spots or pips on each end. They are often twice as long as they are wide and are stacked one on top of the other. Each domino has a value that is determined by the number of dots on either end. The value is called the rank or weight. In addition, dominos have a color code that makes them easier to sort and match in the same line. The color code is usually printed on the edge of each domino.
There are many games that can be played with domino. Generally speaking, the most popular games are positional, where each player in turn places a domino edge to edge against another, forming a specified total. In addition to positional games, dominoes can also be used in a variety of arithmetic and strategy-based games.
A game of domino can be played with a set of any size, though larger sets are more common than smaller ones. A typical domino set has a maximum of about fifty double-six tiles.
Most domino games are played by more than one person, but there are also some solitaire games. In most games of domino, players take turns playing a domino to the table. The first player to play a domino may be known as the setter, downer, or leader, and he will place his tile in the center of the table. The other players will then play their tiles in order to complete the line of play.
The line of play for a particular game is usually, but not always, formed by matching the open ends of two adjacent dominoes. The resulting configuration is sometimes called a string or layout. Regardless of the name for the line of play, basic instructions are given for establishing it in the section below entitled Line of Play.
After each player has drawn the number of dominoes that he is permitted to take for his hand according to the rules of the game, he may draw additional dominoes from the stock if they are required for his play. If he draws more than he is allowed to, these extra dominoes are called overdraws.
Overdraws must remain face down and cannot be passed to the player to his right or purchased (see “Passing and Byeing” below). Occasionally, no one is able to make a play because all of the available dominoes have been drawn. This situation is called a blocked game, and the rules of the game may be modified.
Students can use the dots on a domino to create simple addition equations. The teacher can hold up a domino that has the number 4 on one end and 2 on the other and have the class say an addition equation. The teacher can then demonstrate that if the domino has four on one side and two on the other, the equation is the same whether the numbers are reversed or not. This activity helps to illustrate Mathematical Practice Standard 8, Look for and express regularity in repeated reasoning.