What did McGraw believe was the factor contributing to Johnny's skating ability at less than 1 year compared to Jimmy?

McGraw believed that a lower center of gravity contributed to Johnny's skating ability at a younger age compared to Jimmy. The concept of a lower center of gravity is significant in motor development and balance. In younger children and infants, their body proportions are different—specifically, their heads are larger relative to their bodies, which can influence their stability and balance. A lower center of gravity aids in providing better balance, making it easier for a child to engage in activities like skating.

This understanding emphasizes the physical aspects of development that play a role in motor skills. Children with a lower center of gravity may be naturally more stable when they first engage in new activities, allowing them to develop their skills more readily and successfully, as seen with Johnny.

Other factors like readiness, recklessness, or practice, while important in different contexts, do not specifically address the physiological advantages that come with body mechanics at a young age. Thus, the focus on a lower center of gravity accurately reflects McGraw’s observations about the relationship between physical development and motor skill acquisition in early childhood.