Why are most teenagers so disorganised? And unreasonable? And - well - disconnected? Anyone trying to bring up or teach teenage children wonders the same thing.
The answer is that their brains are changing to equip them with the necessary social skills to survive in the adult world.
Recent research has shown that, as children head towards adulthood, the higher intellectual and emotional parts of their brains show a relative increase in the activity of a neurochemical called dopamine. This process usually starts at around nine or 10 years of age and is pretty much finished by 18. For the teenager, it may feel a bit like being slightly drunk all the time - one of the effects of alcohol is to increase levels of dopamine in the brain - and for the grown-ups observing them, it may look like that, too.
Dopamine secretion, mainly controlled by the brain's emotional system, is central to acquiring mature behaviour, with high levels of its activity promoting learning in the areas related to social skills, which equip adolescents to become effective adults.
And, at this critical time in their development, we hijack the biological imperative and make them learn other things, such as maths and history - then add insult to injury by subjecting them to perpetual testing.
But why should this process make teenagers disorganised, and, if it's all about developing social skills, why should theirs often be so awful?
The answer probably lies in the parts of the brain experiencing the increased dopamine activity. A lot of these are involved in executive function - essentially, planning - and behavioural control. But planning and good impulse control are not easy when your brain is slightly intoxicated.
Added to this is the neurochemical impact of the sex hormones, which stoke up the effects of the increased dopamine activity, especially on impulse control and the need for social stimuli.
So your average teenager is floundering in a complex neurochemical soup and experimenting with novel stimuli. No wonder they don't always get it right.
It is up to us as grown-ups to understand what they are going through and help them become effective adults. After all, our neurochemistry should be stable and established by now Dr Andrew Curran is a paediatric neurologist practising in Liverpool. He also works with Manchester University's department of education on the use of emotional literacy in classrooms
Chambers, R A, Taylor, J R, and Potenza, M N 2003, "Developmental Neurocircuitry of Motivation in Adolescence: A Critical Period of Addiction Vulnerability", The American Journal of Psychiatry, vol. 160, no. 6, pp.
1041-1052. Schultz, W 1997, "Dopamine neurons and their role in reward mechanisms", Current Opinion in Neurobiology, vol. 7, no. 2, pp. 191-197.