The physical development of children between ages 7 and 12 is slower than it had been in the early childhood years, and than it will be in adolescence. This stage of development is often referred to as “middle childhood.” Physical changes that occur in a child in this stage include changes in activity levels, dental changes, possible onset of puberty and maturation of small muscles.
According to Lucile Packard Children's Hospital at Stanford, children in this stage of development gain an average of 2.27 to 3.18kg. while their height increases by approximately 2.5 inches per year. Often, the increases in height and weight occur in spurts. Cliffsnotes explains that children may actually feel growing pains during this time as their skeletal bones and muscles become broader and longer. Also noted, is that generally boys are much smaller than girls at the beginning of this stage but by early adolescence most females are significantly larger than their male counterparts.
Children of this age group will fluctuate between higher and lower energy levels as they transform from a young child to an adolescent. Eating and sleeping patterns will reflect their activity level at the time. Although children this age aren't as physically active as they had been during the early childhood years, they still require an average of 10 hours of sleep daily.
Children will have begun loosing their baby teeth and will continue to do so throughout this developmental stage. Adult teeth will grow in their places, which can sometimes lead to dental crowding. Often this issue resolves on its own once the mouth has finished growing.
Sometimes during this stage the early signs of puberty can begin to show in both genders but especially in females. These changes can include widening of the hips, pubic hair, an increase in height, and development of breasts or testes. At this stage children begin to put more emphasis on gender differences. They will also begin to show more interest in gender appropriate activities.
One of the most drastic physical changes that occurs during the middle child stage is the maturation of small muscles. At the beginning of the stage children are uncoordinated due to immaturity of small muscles. However, by the end of this stage the small muscles are almost fully mature. This occurrence gives the children more highly developed fine motor skills which allows them to partake in actives such as sewing, playing musical instruments and working with tools.