3.1 Physical development during the school years

Although it may be tempting to think that physical development is the concern of physical education teachers only, it is actually a foundation for many academic tasks. In first grade, for example, it is important to know whether children can successfully manipulate a pencil. In later grades, it is important to know how long students can be expected to sit still without discomfort—a real physical challenge. In all grades, it is important to have a sense of students’ health needs related to their age or maturity, if only to know who may become ill, and with what illness, and to know what physical activities are reasonable and needed.

Trends in height and weight

Typical height and weight for well-nourished, healthy students are shown in Table 1. The figure shows averages for several ages from preschool through the end of high school. But the table does not show the diversity among children. At age 6, for example, when children begin school, the average boy or girl is about 115 centimeters tall, but some are 109 and others are 125 centimeters. Average weight at age 6 is about 20 kilograms, but ranges between about 16 and 24 kilograms—about 20% variation in either direction.

There are other points to keep in mind about average height and weight that are not evident from [link] . The first is that boys and girls, on average, are quite similar in height and weight during childhood, but diverge in the early teenage years, when they reach puberty. For a time (approximately age 10-14), the average girl is taller, but not much heavier, than the average boy. After that the average boy becomes both taller and heavier than the average girl—though there remain individual exceptions (Malina, et al., 2004). The pre-teen difference can therefore be awkward for some children and youth, at least among those who aspire to looking like older teenagers or young adults. For young teens less concerned with “image”, though, the fact that girls are taller may not be especially important, or even noticed (Friedman, 2000).

A second point is that as children get older, individual differences in weight diverge more radically than differences in height. Among 18-year-olds, the heaviest youngsters weigh almost twice as much as the lightest, but the tallest ones are only about 10 per cent taller than the shortest. Nonetheless, both height and weight can be sensitive issues for some teenagers. Most modern societies (and the teenagers in them) tend to favor relatively short women and tall men, as well as a somewhat thin body build, especially for girls and women. Yet neither “socially correct” height nor thinness is the destiny for many individuals. Being overweight, in particular, has become a common, serious problem in modern society (Tartamella, et al., 2004) due to the prevalence of diets high in fat and lifestyles low in activity. The educational system has unfortunately contributed to the problem as well, by gradually restricting the number of physical education courses and classes in the past two decades.