Middle Childhood: Body, Mind, and School

This is Unit Seven, part one, on the school-age body and brain, health, and thinking in middle childhood. Unit Six closed on media and watching together. Unit Seven follows children from about seven to eleven, into school. Carry one question through this part: is the school-age mind a new kind of thinker, or a faster version of the one before? At the entry on concrete operations, Piaget answers: a new kind, with logic about real things. At the entry on information processing, a second account answers: faster and more efficient. The part holds both. By the end you will be able to tell lateralization from the work of the corpus callosum. To name the concrete operations. To say what cross-cultural research shows about Piaget's ages. To name three memory strategies. And to explain what the heritability of intelligence does and does not mean.

Six entries on the body and brain from seven to twelve, and on the motor skills that grow with them.

How children grow in these years.

HGD 0901 Growth in Middle Childhood

Growth in middle childhood is slower and steadier: about two to three inches and five to seven pounds a year until puberty. Boys and girls are similar in size at seven; girls, entering puberty earlier, are often briefly taller than the boys in their class, and after boys' puberty most boys are taller and heavier.

What shapes height.

HGD 0902 Height, Genes and Environment

Height is strongly heritable, but heritability describes variation across a population, not how much of one person's height genes produce. Undernourishment, childhood disease or severe neglect can produce stunting, a child far shorter than expected, which is linked to behavioural and cognitive problems.

The brain at seven.

HGD 0903 The Brain at Seven

By seven or eight the brain reaches about ninety-five percent of adult size, and myelination and synaptic pruning continue, speeding processing. The prefrontal cortex, serving logic, planning, memory and attention, changes most. Neuron numbers change little; gains come from stronger connections.

Two terms that are often confused.

HGD 0904 Corpus Callosum and Lateralization

Lateralization is the specialization of a function to one side of the brain, such as language production in the left hemisphere of most right-handed people. The corpus callosum, maturing now, carries coordination between the hemispheres. The two are often confused: specialization is lateralization; communication across is the corpus callosum's work.

Motor skills from seven to twelve.

HGD 0905 Motor Skills, Seven to Twelve

Gross motor skills such as balance, running and throwing, and fine motor skills such as writing and tying laces, both advance in middle childhood; a ten-to-twelve-year-old can high-jump about three feet and draw detailed pictures. In one study by Cameron and colleagues, well-developed fine motor skills went with better mathematics and reading achievement.

Culture and fine motor skill.

HGD 0906 Culture and Fine Motor Skill

Culture shapes motor skill: Hong Kong children, with early practice using writing tools and chopsticks, outperformed US children on fine motor tests; a six-year-old can pick up a single grain of rice with chopsticks. Group differences in motor skill reflect childrearing and exposure, not fixed ability.

Seven entries on health in the school years, from sleep and weight to injury and chronic illness.

Sleep from six to twelve.

HGD 0907 Sleep, Six to Twelve

The American Academy of Sleep Medicine recommends nine to twelve hours of sleep a night for children aged six to twelve. Sleep consolidates learning and releases growth hormone. Occasional disruptions are normal, but persistent sleep problems carry emotional, behavioural and school risks.

Childhood obesity.

HGD 0908 Childhood Obesity

Obesity, a BMI-for-age at or above the ninety-fifth percentile, affects nearly nineteen percent of US school-aged children, nearly double over several decades, and overweight, the eighty-fifth to ninety-fifth percentile, covers another sixteen. Risks include high blood pressure, insulin resistance and type two diabetes, and effects on mental health and achievement.

Two forms of undernutrition.

HGD 0909 Undernutrition: Wasting and Stunting

Undernutrition in childhood takes two main forms: wasting, being too thin for one's height, and stunting, being too short for one's age. Both raise the risk of illness and of poorer cognitive and mental health, risks that nutrition programmes, such as school meals, reduce.

Exercise, and what gets in the way.

HGD 0910 Exercise and Its Barriers

The CDC recommends at least an hour of moderate-to-vigorous activity each day for children, with benefits for body, cognition and emotion, yet most children fall short. Barriers include poverty, lack of social support, climate, neighbourhoods without safe places to play, and cultural roles that discourage girls' sport.

Injury, and its prevention.

HGD 0911 Injury and Prevention

Unintentional injury is a leading cause of death and disability in childhood, and prevention, seat belts, bicycle helmets, swimming lessons, life jackets and locked medicines, has cut injury deaths in higher-income countries. Injuries fall hardest on lower-income countries. In the US, firearms were the leading cause of death at ages one to nineteen in twenty twenty-two.

Asthma.

HGD 0912 Asthma

Asthma, chronic inflammation of the airways, affects about eight percent of US children, and family history, allergies, urban air pollution and obesity raise the risk. Poorly controlled asthma is a leading cause of school absence, and chronic illness is linked to behavioural and socioemotional concerns as well as missed learning.

Diabetes, and health disparities.

HGD 0913 Type 1 and Type 2 Diabetes

In type one diabetes the immune system destroys the body's capacity to make insulin; type two involves insulin resistance, is often preventable, and, once called adult-onset, is now rising among children. Obesity, diabetes, asthma, injury and poor nutrition fall more heavily on lower-income and historically marginalized groups, through access to food, care and cleaner air.

Five entries on Piaget's third stage and what later research changed. The first answer to the opening question comes here.

Piaget's third stage.

HGD 0914 The Concrete Operational Stage

Piaget's concrete operational stage, from about seven to eleven, brings logical thought about concrete, tangible problems, but not yet abstract or hypothetical ones: a nine-year-old solves a problem with blocks on the table, then is stumped when it is posed hypothetically. Operations are logical mental actions that can be reversed.

The operations themselves: the first answer.

HGD 0915 Concrete Operations

Concrete operational children master a set of operations, and here is Piaget's answer to this part's question. Conservation: an amount stays the same despite changes in appearance. Decentration: attending to height and width at once. Reversibility: mentally undoing a sequence. Class inclusion: there are more fruit than apples. Seriation: ordering sticks from shortest to longest. Transitive inference: if A is taller than B and B taller than C, then C is shortest. A ten-year-old watching juice poured into a tall glass says it's the same, because you can pour it back. Egocentrism also declines, and the type of conservation mastered first can differ with culture.

Culture and Piaget's ages.

HGD 0916 Culture and Piaget's Ages

Cross-cultural research in Bali, India and Nepal finds Piaget's sequence of stages generally holds, but the ages at which children reach them vary. The misconception is that the stages start at fixed ages everywhere; the order holds broadly, and timing depends on experience.

Evidence against strict stages.

HGD 0917 Less Stage-Like Than Piaget Thought

Cognitive development may be less stage-like than Piaget proposed: some children show concrete operations before seven, and in McGarrigle and Donaldson's study preschoolers passed a conservation task early. Active learning supports these gains. One study suggests some children now reach stages later than thirty years ago.

Screens in middle childhood.

HGD 0918 Screens in Middle Childhood

More than about two hours of screen use a day is linked to physical, behavioural and academic problems, though benefits depend on content and use: a designed educational game is not hours of passive scrolling. The AAP no longer sets strict limits for this age, asking families instead to protect sleep, activity and quality content.

Seven entries on the mind as a processor: attention, memory, strategies and self-monitoring. The second answer comes here.

The second answer: information processing.

HGD 0919 Information Processing at School Age

The information processing approach compares the mind to a computer and describes quantitative, continuous change: children become faster and more efficient, choosing what to attend to, holding it longer and using strategies to remember it. That is the second answer to this part's question. Unlike Piaget's stage theory, it is the work of many researchers, and it describes gradual rather than stage-like change.

Two kinds of attention.

HGD 0920 Selective and Sustained Attention

Selective attention is focusing on what matters while ignoring distraction, like a child reading in a noisy classroom; sustained attention is staying with one task over time. Both improve in middle childhood. Selective attention is linked to temperament and self-regulation, and anxiety, task difficulty and skill all limit attention capacity.

Working memory, and encoding.

HGD 0921 Working Memory and Encoding

Working memory combines attentional control with short-term storage and active manipulation; encoding moves information into long-term memory. Both improve markedly in middle childhood, as when a child recalls a ten-item shopping list by grouping it into fruit, dairy and bread.

Three memory strategies.

HGD 0922 Memory Strategies

Three encoding strategies grow in middle childhood. Rehearsal is repeating information to keep it in mind. Elaboration is linking new information to what one already knows. Organization is grouping and ordering information, such as sorting a list into categories. Children begin using strategies around five or six, use them efficiently around seven, and keep improving to about ten, according to Schneider and colleagues. Exam items describe a strategy and ask its name: repetition is rehearsal, connection to prior knowledge is elaboration, grouping is organization. Strategy use grows alongside metamemory.

Thinking about one's own thinking.

HGD 0923 Metacognition and Metamemory

Metacognition is knowing how one thinks and learns and using that knowledge, like a student who notices she has lost the thread and rereads. Metamemory is understanding how memory works, such as short lists being easier. Younger children overestimate their memories; the accuracy of their self-judgements improves into adolescence.

Executive functions.

HGD 0924 Executive Functions

Executive functions are skills for regulating behaviour toward goals: working memory, attentional control, inhibition, mental flexibility, planning and organization, as when a child packs her school bag the night before. They develop through adolescence with prefrontal maturation, are shaped by warm, responsive parenting, and predict achievement and social behaviour.

Theory of mind at school age.

HGD 0925 Theory of Mind at School Age

Theory of mind keeps developing after five and is linked to reading comprehension, grasping characters' minds, and to scientific reasoning, as when a ten-year-old explains why a character in a novel lied. Culture matters: a study comparing Iran and Australia found children passed theory-of-mind steps in a different sequence, not merely later.

Four entries to close the part, on intelligence: what it is, what shapes it, and a single general ability.

What intelligence is.

HGD 0926 What Intelligence Is

Intelligence, broadly, is the ability to adapt to the world, including creativity, problem-solving, abstract reasoning and learning, in Sternberg's description, like a child working out a new game's rules without instructions. Unit one's reaction range applies: genes set a range, and environment decides where within it a child's ability falls.

Genes and intelligence.

HGD 0927 Genes and Intelligence

Twin and adoption studies show genetic influence on intelligence, and genome-wide studies point to many genetic variants, each with a small effect. There is no single intelligence gene, and heritability describes variation across a population, not how much of one child's ability is inherited.

The environment's part.

HGD 0928 Environment and Intelligence

Environment shapes intelligence: prenatal or childhood exposure to radiation or lead lowers it, while daily breakfast, stimulating experiences and resources support it. Lower-income children score lower on average, largely through differences in access to resources. Parents' growth mindset is associated with children's persistence and reading, an association rather than proof of cause.

General intelligence.

HGD 0929 Spearman's g

Spearman proposed general intelligence, g, a single ability underlying performance across tasks, plus specific abilities for particular tasks. Binet and Simon had noticed that children who did well on one test task tended to do well on others; Binet's test was built for the French government to identify children who needed extra support in school.

Look at what you can now do. You can tell lateralization, one side specializing, from the corpus callosum's work, communication between the two. You can name the concrete operations: conservation, decentration, reversibility, class inclusion, seriation and transitive inference. You can say what cross-cultural research shows: Piaget's order holds broadly, while the ages vary with experience. You can name three memory strategies: rehearsal repeats, elaboration connects, organization groups. And you can explain that intelligence is shaped by many genes of small effect and by the environment, and that heritability describes a population, not one child. Part two covers fluid and crystallized intelligence.