A back scale in gymnastics is a balanced move where the gymnast stands on one leg while lifting the other leg behind them, parallel to the ground. The body forms a straight line from the head to the raised foot, and the arms are typically extended for balance, demonstrating control, flexibility, and strength. To perform the back scale, start by standing upright with your feet together. Slowly lift one leg straight back, keeping it parallel to the ground. Extend your arms in a 'T' to the side for balance and ensure your body forms a straight line from head to lifted foot. Engage your core to maintain stability and hold the position. Finally, lower your lifted leg back to the starting position smoothly.