It is the first day of term and you’re in Primary 1 (equivalent to Reception in England) with a group of children who are not toilet-trained, who can’t control their impulse to move about, shout out or bash another child. And then there are the passive children, good at staring but short on language, interest and emotion.

Teachers have to work with the children that parents send to school. What can be done to improve the situation? Nursery workers are in a similar position: many of their two- and three-year-olds are not ready for day care.

However, it is well established that child behaviour and attainment benefits from early support for children and parents. Yes, that support has to extend to parents, too - they are each child’s most influential teacher. This is a big issue.

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In the next five years, 250,000 children will be born in Scotland. That is the equivalent of the population of Aberdeen, combined with Hamilton.

How many of those children will be vulnerable when they reach P1? By vulnerable I mean lacking in one or more of social competence, emotional maturity, language and cognitive ability, physical health and wellbeing, fine motor skills and communication skills. Relying on the early development indicator applied across all pupils entering primary school in East Lothian, for example, the answer is this: one in every four children is vulnerable.

Early years: parental engagement

Extrapolating that finding to the national scene suggests that, in five years’ time Scotland will have added the equivalent of another Hamilton (population 53,000, according to the 2011 census) of vulnerable children.

Parents play an enormous role in child development. There is a glimmer of hope on the horizon, however: that intergenerational failure - the baton-passing of neglect and dysfunction from grandparents to parents to child and then to their offspring - will soon start to be arrested. A commitment has been made by the Scottish government to double the amount of day care available to vulnerable two-year-olds and all three- and four-year-olds. It remains to be seen, however, whether the results of this initiative might be for good or for bad.

Human babies come into the world needing more support and for longer than any other species: at 40 weeks a baby may have a full set of toes and fingers, but its brain has not yet completed development.

Babies have a powerful need to be close to their parent or carer. A two-way attachment takes place between the mother (and father) and the baby. A cry is let out and the baby is picked up, cuddled, a “goo-goo” sound is made…if the cry persists, the nappy is checked, food provided or the child is encouraged to sleep. On an hourly and daily basis, this dance takes place between parent and child, which builds up trust, confidence, safety, stimulation and communication. Mutual attachment grows and protects the relationship and sets the baby up to grow and flourish.

In some houses, and for some parents, however, this does not happen. For some babies, life is a continuous ordeal of living with stress. Am I going to be hugged or ignored? Will harsh voices or something worse come my way? These babies live with stress and strangers.

What role does the expansion of day care play in the delicate balance between babies, parents and services? On a recent visit to a combined day care centre and primary school in the East End of Glasgow, I was told by the headteacher: “I am fearful of the unintended consequence [that] parents could become more deskilled.”

In her day-care centre, contact and nurturing of parents is given priority. But that is not always the case. Rules on day-care funding, muddled objectives and measurement, local management and busy parents can conspire to create a “click and collect” service for two- and three-year-olds.

Child development is like the building-block game Jenga, where you create a tower by putting one slab of wood on top of another. It is sequential: if you do not get the right steps of child development in order, then the next step is impaired or just does not take place. The most important block in this version of Jenga, for good or bad, is the block of wood with “parents” marked on the side.

To give all children a decent chance of progressing in life - and to stop primary teachers drowning - there is a need to shift our framing of early education. What parents, health visitors and nursery staff do is of vastly more significance than is commonly appreciated.

Gearing up day care, if done in the right way, alongside parents, can make a difference. This is not about making perfect parents: it is about helping parents to make progress so that they can enjoy their children and, in turn, help them to thrive - and an unintended consequence would be primary teachers having a better life.

Alan Sinclair is founding chief executive of the Wise Group social enterprise and author of Right from the Start