was also pair ballet competitions, a variation of ballet, where two people performed tricks that not only included spins, jumps and leg crossing but also lifts and sychronic movements and was similar to ice dancing. The routines were scored by judges who assessed the choreography, technical difficulty, and mastery of skills demonstrated by the competitors. Early innovators in the sport were American Jan Bucher, Park Smalley, Swiss Conny Kissling and German Hermann Reitberger. The first skier who performed a one handed pole flip in a world cup competition was German Richard Schabl in the early 1980s. Acro ski was part of the demonstration at the 1988 Winter Olympics in Calgary. The International Ski Federation ceased all formal competition of this event after 2000 because they focused on both aerials (1990) and moguls (1992) for making it an Olympic discipline. Ski cross Ski cross is based on the snowboarding boardercross. Despite it being a timed racing event, it is often considered part of freestyle skiing because it incorporates terrain features traditionally found in freestyle. Halfpipe skiing Halfpipe skiing is the sport of riding snow skis on a half-pipe. Competitors gradually ski to the end of the pipe by doing flips and tricks. It became an Olympic event for the first time at the 2014 Olympic Games in Sochi, Russia. Slopestyle In slopestyle, athletes ski or snowboard down a course including a variety of obstacles including rails, jumps, and other terrain park features. Points are scored for amplitude, originality and quality of tricks. Twin-tip skis are used and are particularly useful if the skier lands backwards. Slopestyle tricks fall mainly into four categories: spins, grinds, grabs and flips. Slopestyle became an Olympic event, in both skiing and snowboarding forms, at the 2014 Winter Games in Sochi, Russia. Equipment Twin-tip skis are used in events such as slopestyle and halfpipe. Mogul skis are used in moguls and sometimes in aerials. Specially designed racing skis are used in ski cross. Ski bindings took a major design change to include plate bindings mounted to the bottom of the skiers boot to allow for multi-directional release. Ski poles are a staple in the all aspects of freestyle skiing, however, slopestyle athletes have more recently opted to ski without them in order to free their hands for grabs and other personal preferences in their riding. See also Freestyle skiing at the Winter Olympics FIS Freestyle World Ski