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Notions of symmetry can begin with identifying patterns whose appearance stays the same when they undergo some change ( such as rotation , reflection , stretching , or displacement ) . But more typically , symmetry implies a pattern whose appearance stays the same when it undergoes a change such as rotation , reflection , stretching , or displacement . Current treatment strategies include pain medication , exercise , stretching , sleep management and psychological support . The first lesson often begins with basic safety policies , stretching , and learning to fall , then progresses to snowboarding with one foot on the board ( particularly skating and S-turns ) . In fact , he did this pushing , stretching , and tearing apart throughout his career .