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Module 2: Physical Development

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Trends in Height and Weight

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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, e.g. it is important to know whether children can successfully manipulate a pencil or how long students can be expected to sit still without discomfort.

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.

The table on the right shows typical height and weight for well-nourished, healthy students. 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 centimetres tall, but some are 109 and others are 125 centimetres. 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 the table on the previous screen. 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 favour 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.

The third point to keep in mind is that average height and weight is related somewhat to racial and ethnic background. In general, children of Asian background tend to be slightly shorter than children of European and North American background. The latter in turn tend to be shorter than children from African societies (Eveleth & Tanner, 1990).

Body shape differs slightly as well, though the differences are not always visible until after puberty. Asian youth tend to have arms and legs that are a bit short relative to their torsos, and African youth tend to have relatively long arms and legs. The differences are only averages; there are large individual differences as well, and these tend to be more relevant for teachers to know about than broad group differences.