The four stages of development

1. Development is the pattern of physical, cognitive and social change that runs from conception to old age.
2. It is split into four stages: pre-natal, childhood, adolescence and adulthood.
3. Each stage brings its own physical growth and its own new ways of thinking.
4. The four stages arrive in the same fixed order for everyone, because each one waits on the maturation of the body and the nervous system.

What changes in each stage

1. Pre-natal
   1. This runs from conception to birth.
   2. The body and the brain form quickly, and neurons are produced and start to connect well before birth.
   3. What reaches the foetus can disrupt this, including poor diet, illness, alcohol and smoking.
   4. A baby is born with most of its neurons already in place, and experience connects them up.
2. Childhood
   1. This runs from birth to around eleven and is the fastest period of learning after birth.
   2. Movement, the senses, language and memory all develop rapidly in the early years.
   3. Thinking becomes steadily more logical, so a child who judges by appearances at four reasons about quantity at seven.
   4. In the brain, connections that get used are strengthened and unused ones are lost.
3. Adolescence
   1. This begins with puberty, when hormones trigger a growth spurt and sexual maturity.
   2. The brain reorganises, and the frontal areas behind planning and self-control are the last to finish maturing.
   3. Abstract and hypothetical reasoning becomes possible, so a teenager can argue about ideas they cannot see or touch.
   4. Strong emotions and risk-taking are common while that self-control is still catching up.
4. Adulthood
   1. Physical growth is complete and thinking is at its most efficient.
   2. Learning carries on, because the brain can still form new connections throughout adult life.
   3. In later adulthood processing can slow, although knowledge built up over a lifetime is largely kept.

Maturation and the order of the stages

1. Hypothetical reasoning appears only once the brain has built the structures it runs on, so a two-year-old does not reach it however carefully they are taught.
2. Children in very different countries reach the same kinds of thinking at roughly the same ages.
3. Teaching and practice change how far a child gets within a stage, so two eight-year-olds can be at very different levels.

The nervous system

1. The nervous system has two divisions: the central nervous system, which is the brain and spinal cord, and the peripheral nervous system, the nerves that run to the rest of the body.
2. Both keep maturing through childhood and adolescence, and the myelin that speeds signals along the nerves is still being added into the early twenties.

Turning this into marks

1. When two stages are asked for, name each one and give a change that belongs to that stage alone rather than one change reworded.
2. Name maturation, because saying that children grow up and get better at thinking does not secure the knowledge mark.
3. The mark most often lost is giving ages instead of changes, so pair every stage you name with what develops in it.