The rate of growth slows during the preschool years. Children gain about 2.3 kg (5 lb) each year and grow taller by 6.0 to 7.5 cm (2 to 3 inches) per year (Table 31-1). Although few physical differences between boys and girls are evident during this time, there is increasing variability among individual children.

While most of the increase in height occurs in the legs, the chubby pot-bellied body of the toddler gives way to a more slender and posturally erect profile. Preschoolers are better coordinated than their younger selves. By age 3, children are walking, running, jumping, and climbing well. Their sense of balance improves markedly. A 3-year-old can stand on one foot for a few seconds; by age 4, the same child is hopping around on one foot. At 3 years, most children are riding a tricycle; by 6 years, many have mastered riding a two-wheel bike. At 3 years, children can go upstairs using alternating feet, but still descend placing both feet on each step. By age 4, they descend using alternating feet, holding the railing. At age 6, they are running up and down stairs easily (Table 31-2).

Muscles and bones are not yet fully developed, however. While most preschoolers appear sturdy, able, and motivated, they are not physically ready for athletic activities that require endurance and coordination for sustained periods of time. This age group is also reckless owing to a lack of judgment and impulsiveness. Injuries are the leading cause of death between ages 1 and 4.

Fine motor skills also improve markedly as preschoolers use their hands as tools. They enjoy projects that involve finger painting, working with Play-Doh, pasting, and coloring. They build with blocks, put together large-piece puzzles, and zoom little cars around toy villages. They button and zip, although tying shoelaces takes much practice.