Certain changes in body growth, the brain, and motor development in middle and late childhood. - Skeletal and muscular system: Slow, constant development characterizes the middle and late childhood years. - During this time, children grow 2 to 3 inches each year on average. - Muscle mass and strength grow gradually. - The changes in head circumference, waist size, and leg length in proportion to body height are among the most noticeable. The brain - It is evident that changes in the brain continue to occur in middle and late childhood. These changes are greater myelinations, which are found to be associated with improved cognitive ability. - There is an increase in networks involving the prefrontal cortex, which is associated with increased attention, thinking, and cognitive control. - Thus, less diffusion and more localized activation occur in the prefrontal cortex between middle and late childhood, which is related with an improvement in cognitive control.