A game of curling is divided into ends, usually eight or ten ends, lasting 15 minutes each. Teams alternate throwing eight stones each, for a total of 16 stones. After these 16 stones are thrown, it is time to score the end. When scoring an end, only one team is allowed to score. Also note that each stone is worth only one point and that the colors of the rings in the house do not affect how many points are scored.
To score an end of curling, the first step is to see what stones are in the house. If there are no stones in the house, a blank end occurs, and no team scores points. If there are stones in the house, we need to figure out which team scores, and how many points they scored. We will break the scoring down into three steps:
The Button is the smallest circle and is 1 foot in diameter. The 4 Foot is the second smallest circle and has a diameter of 4 feet. Similarly, the 8 Foot and 12 Foot have diameters of 8 and 12 feet, respectively.
After we find the stone that is shot rock, we are able to determine that the team with the shot rock will score the points for the end. Since each rock is worth one point, the team with the shot rock is guaranteed to score 1 point. Now, we move on to see which other stones count.
When determining which other stones count for scoring, follow this rule: the team that scores earns a point for every stone that is closer to the Button than the opponent's closest stone to the Button. All this really means is to count the number of stones that belong to the team with the shot rock until the other team would have the shot rock. For example, if the Red Team had 2 stones in the 4 Foot, and the Yellow Team had 1 stone in the 12 Foot, the Red Team would score 1 point for the shot rock, and an additional point because their second stone (or second shot rock in this case) is still closer than the opponent's shot rock.
To summarize this, find the actual shot rock and the opponent's shot rock. However many stones in addition to the shot rock are closer than the opponent's shot rock score. Therefore, if the Red Team has 1 stone in the 4 Foot and 1 in the 12 Foot, but the Yellow Team has 1 stone in the 8 Foot, the Red Team can only score 1 point. This is because the Red Team has the shot rock, and the Yellow Team has the second shot rock, and is closer than the red stone in the 12 Foot.
If there is an instance in which teams cannot decide if one stone is closer than another, a micrometer (or measuring device) is employed. A micrometer is a large metal bar with an adjustable pressure gauge so that it can more freely to the stones in contention and then lock into place. One end of the micrometer is placed in the pin (the exact center of the house), and the pressure gauge is adjusted to just touch an edge of one of the stones in contention. The micrometer will pass by both stones and display a pressure reading.
The stone that produces the higher pressure reading is the stone closer to the Button. Most of the time, it is fairly easy to tell which stone is closer, but there are times where you may need to pass the micrometer by both stones again. Then, the scoring rules from the previous section apply.