1. Curling, which traces its roots to the 1500s, first became an organized sport in Scotland in the 19th century.

2. The stone, or rock, is made of granite and weighs 38 to 44 pounds.

3. The players' feverish sweeping polishes the ice to help the stone travel farther and curl less.

4. Curling debuted at the Olympics in 1924 but didn't return as an official competitive event until the Winter Games of 1998.

5. Curling is played worldwide, but is most popular in Canada.

More: Watch introductory videos about curling at www.startribune.com/a1105.

Source: World Curling Federation