The primary years are engraved in most people’s memories as a rite of passage from the intimacy and informality of home to a more public and formal life. In 1900 criticism was being levelled at the “babies’ classes”, where children as young as three spent long hours seated in serried rows.

As our century ends, arguments rage about the fate of four-year-olds in reception classes where baseline assessment and the goals of early learning too often result in a rigid regime at too young an age.

Primary school buildings in every locality stand as monuments to changing ideals and practices. Quaint Gothic schoolrooms in villages, more often now converted to desirable residences, and towering Victorian board schools still in use in the big cities, are reminders of the educational inheritance that the 20th century came into, denominational effort and municipal enterprise.

The interwar suburbs are home to more inviting single-storey redbrick buildings, a less intimidating vernacular with a hint of classicism to convey their serious purpose, and surrounded by ample playing fields. Post-war modernism bequeathed walls of glass that opened up the classrooms, and landscaped school grounds with nature areas and adventure playgrounds.

Buildings outlive the educational fashions that designed them and inside the school, the pupils, teachers and the curriculum continue changing and adapting to new cultures, technologies and curriculum prescriptions. At the century’s beginning, these schools were designated “elementary”. Often colloquially “working-class schools”, they were intended for the majority as a complete education from age 5 to 14. “Elementary” became “primary” as developmental psychology began to enlighten practice.

Children, the most constant factor in school, are now better fed, fitter and far more knowledgeable than they were. Schools were identified as one means of remedying the nation’s appalling physical health. So the school nurse, doctor, dentist, school meals and free milk became integral features for many decades. Thatcherism saw these welfare aspects as redundant, and from the 1980s they were deliberately run down, but only as other physical and psychological health issues such as obesity, bullying and child abuse became a concern of the primary school.

Young children still need protection, as well as literacy and numeracy, but the globalisation of their cultural world offers a different challenge to their teachers. Primary pupils have become sophisticated consumers in their own right, media-watchers and web-surfers. Primary teachers have changed even more.

At the turn of the century, under half were college-trained and schools still depended heavily on untrained “supplementary” teachers and “pupil-teachers” in training. The marriage bar forced a cruel choice on many women as a teaching career meant “spinsterhood”, with all that implied in terms of social status.

But a shortage of careers for educated girls meant a continuing ready supply of teachers. Primary teaching became an increasingly feminised profession as all-through elementary schools were “decapitated” by inter-war reorganisation and older children moved to “senior elementary” or “secondary modern” schools were taken on disproportionately by male teachers.

The double bind for women was that headships of combined infant and junior schools most often went to male candidates, on the assumption that a man could not serve under a woman.

The Second World War prompted change, as mothers were called back into teaching, and teacher shortages resulting from the post-war baby boom opened more opportunites for “married woman returners”.

Elementary-trained teachers found their way into an expanded secondary sector just before and after the Second World War, and the perception was gradually entrenched that “subject knowledge” was not enough.

Educational theory developed in its sophistication, and understanding developmental psychology became a sine qua non for primary teachers. The primary training curriculum in the early 1960s expanded rapidly from the traditional two-year to a three-year certificate course and then the Bachelor of Education degree. By the 1970s, degree-level entry was stipulated for all primary teachers (and professional training for all secondary teachers) promoting a more equal status between the two stages.

The primary curriculum is the most visible aspect of change. Passive, desk-bound learning was the order of the day in most elementary schools before and after the First World War. Drill, maypole dancing and Empire Day celebrations provided some light relief, and from the earliest years of the century the “school journey movement” was under way.

Developmental psychology increasingly encouraged a more active curriculum and technologies such as the car and broadcasting made this ever more possible. Learning by doing became more than an educational dogma, rather a cultural necessity.

For all the rhetoric of “back to basics” and “Victorian values”, without the development of educational theory and professionalisation of primary teaching the primary years of schooling would not occupy the political spotlight the way they do today. It is not just technology and globalisation that have made primary schools the sophisticated institutions they are at the turn of the 20th century.

Dr Peter Cunningham is reader in the history of education at Homerton College, Cambridge, and co-author of the forthcoming book, Elementary School Teachers 1918-1939