71 Prelude to Middle and Late Childhood

Overall physical growth: Rates of growth generally slow during these years. Typically, a child will gain about 5-7 lbs a year and grow about 2-3 inches per year (CDC, 2000). They also tend to slim down and gain muscle strength and lung capacity, making it possible to engage in strenuous physical activity for long periods of time. The beginning of the growth spurt, which occurs prior to puberty, begins two years earlier for females than males. The mean age for the beginning of the growth spurt for girls is nine, while for boys it is eleven. Children of this age tend to sharpen their abilities to perform both gross motor skills, such as riding a bike, and fine motor skills, such as cutting their fingernails. In gross motor skills (involving large muscles) boys typically outperform girls, while with fine motor skills (small muscles) girls outperform the boys. These improvements in motor skills are related to brain growth and experience during this developmental period.

Brain growth: Two major brain growth spurts occur during middle to late childhood (Spreen, Riser, and Edgell, 1995). Between ages six and eight, significant improvements in fine motor skills and eye–hand coordination are noted. Then between ten and twelve years of age, the frontal lobes become more developed and improvements in logic, planning, and memory are evident (van der Molen and Molenaar, 1994). Myelination is one factor responsible for these growths. From ages six to twelve, the nerve cells in the association areas of the brain, that is those areas where sensory, motor, and intellectual functioning connect, become almost completely myelinated (Johnson, 2005). This myelination contributes to increases in information-processing speed and the child’s reaction time. The hippocampus, responsible for transferring information from the short-term to long-term memory, also show increases in myelination resulting in improvements in memory functioning (Rolls, 2000). Children in middle to late childhood are also better able to plan, coordinate activity using both left and right hemispheres of the brain, and control emotional outbursts. Paying attention is also improved as the prefrontal cortex matures (Markant and Thomas, 2013).