# The Basics of Domino

Domino is a flat, thumbsized rectangular block with each end either blank or bearing from one to six spots–called pips. A complete set has 28 such dominoes, although larger sets are available.

When a domino stands upright, it has potential energy that physics describes as stored in its position. But when it falls, much of that potential energy converts to kinetic energy, the energy of motion.

## Rules

Dominoes are rectangular pieces that are marked with a number on one side and blank or identically patterned on the other. Each domino also has a special marking called a “spinner” that indicates the value of each end.

In general, dominoes are laid so that touching ends match (one’s touch two’s, for example), and doubles are played at right angles to the line of play. When played, the pips on all exposed ends must be a multiple of five to score points.

The order of play is determined by drawing lots or by the seating arrangement. The player making the first play may be referred to as the setter, the downer, or the lead.

Once a player has a domino train, he places a marker on it. This stops other players from adding to it. A hand is won when all the dominoes in a player’s train are played, or when one player runs out of pieces.

## Materials

Originally dominoes were carved from animal bones, sometimes even ivory for the wealthier players. They were smuggled into Britain in the 18th century by prisoners of war who would carve and sell them for money. Today, dominoes are mostly made of a variety of materials.

In the 19th century cheap dominoes were mass produced from tinplate and distributed for free or for a small fee in pubs and Inns by tobacco companies. The next big breakthrough came in 1856 with the invention of a manmade plastic called Parkesine or Xylonite or Celluloid. This was a very popular material for making dominoes until it proved to be unstable and unreliable.

Another interesting use for dominoes is as a hands on model for explaining how sound travels through an object. By placing two sets of dominoes close together (or spaced out) and allowing one to fall, students can see how spacing affects the speed at which the sound travels through them.

## Variations

There are many different variations to domino games. Some involve the use of a hexadecimal number system to identify individual tiles, while others have rules based on the number of dots on each end of a domino. The most common way to play a domino game is by using positional dominoes, which are played edge to edge with one another and form a chain. In these games, a player may not play a tile that shows the same number on both ends of the chain. This is called a stitch and is considered distasteful by opponents.

Typically, a double domino is used to mark a player’s train. Players then place their own tiles on the line of play. A double domino can also be used as a spinner, allowing the line of play to branch. Some games also have rules for how to draw new hands or score the game. For example, some games count the total number of pips left in losers’ hands at the end of a hand or game and add this to the winner’s score.

## Scoring

A variety of scoring systems exist for domino. Some of these involve keeping a running score and others are more focused on the configurations of tiles or emptying one’s hand.

The most common form of scoring is based on the total number of pips on two exposed ends (a double counts twice). This number is used to decide whether or not a domino scores points in games such as 5s and 3s.

In some scoring games, players may earn bonus points for certain configurations of the tiles. For example, Hector’s Rules allows a player to remove the middle tile on a line of dominoes if it shares a common number with the adjacent tiles.

Another scoring variation is called Concentration. This game is normally played with a set of double-six dominoes and each player has their own grid of 4 X 7 face down. Each turn, a player will flip over two tiles and if the pips add up to 12 they are scored.