Opinion: watching the demolition of her own elementary school, Alexandra Lange reflects on the increasingly generic design of schools, museums and playgrounds that resign children to "places where all they can learn are the tasks we set them."

They tore down my elementary school last week. The demolition of childhood memories is enough to make anyone nostalgic, but in this case, there was something more. My school, Martin Luther King Jr. Elementary School in Cambridge, Massachusetts, was designed by Josep Lluís Sert: Modernist master, former Harvard Graduate School of Design dean, and architect of the superb Peabody Terrace apartments just across the street. I didn't know Sert designed my school until last year, but the building had its effects. When I started kindergarten in 1977, the building was just six years old. I may have lived in a Victorian house, but I learned and played in a thoroughly contemporary environment, with red Tectum walls, folding retractable partitions and clerestory light.

Although I had not been back inside since my family moved in 1982, I could still draw a rough plan from memory. The kindergarten classrooms, each with its own outdoor space, lined up along Putnam Avenue. The light-filled central hall, an indoor thoroughfare entered from the street or from the playground behind, that linked auditorium, gym, cafeteria, classes. The recessed, mouth-like entrance, echoing with noise before the doors opened in the morning. The sense of progression as you aged up, from front to back, downstairs to upstairs. The architectural meaning was clear: protective of the little ones, offering more territory as you grew older. This was a building for children with a cast-in-place pedagogy.

Like the similarly demolished Prentice Women's Hospital in Chicago, the exterior suggested something of the fortress, but the interior was warm and light, shaped by its program. But a change in technology and teaching methods – the new project brief includes breakout spaces, computer labs and ENO Boards – need not have doomed a building based on a grid of concrete columns and floors. The photographs I took of the King School in its half-demolished state suggested a possible future as well: the rhythmic frame as a set ready to be recycled, a new school on an old base that utilised its embodied energy rather than eliminating it.

Looking at the rendering posted on the construction fence, then back up at the exposed reinforcing bars, I see a loss greater than my experience, or for Modernism. I see another space for children made more generic, our mania for safety and uniformity consigning children to a world of tan boxes tricked out with primary-coloured objects. How can you learn about the world in spaces without character?

Across Boston, a number of other Sert buildings have been (or are in the process of being) renovated, including Peabody Terrace, the Boston University School of Law and an office building at 130 Bishop Allen Drive. Harvard has plans to renovate his Holyoke Center, and has hired Hopkins Architects to do the job: in the future, it will be a central meeting point for the university's diverse schools, students and programs.

Why was the fate of the King School different? According to advocates, reuse was a hard sell. Like so many of its Brutalist brethren, the school was not popular in its immediate neighbourhood, despite that neighbourhood being a striking collection of postwar low- and high-rise buildings. In focusing on the building's past and pedigree, preservationists may have neglected to offer a vision of how the building might be born again and added to. Perkins Eastman's feasibility report gives short shrift to this option, accentuating the negative.

If the new design filled me with interest, joy or curiosity I might be less sad, but as a collection of tan boxes arranged along a circulation spine and presented to the community with an arsenal of contextual photos, it makes me feel nothing. Like so many other spaces for children – schools, museums, playgrounds – it looks like the box that the toys come in. Fine when the creative child can turn that box into a toy. Less interesting when the adults decide which way is up and which colours connote the most fun. In such spaces, the engagement and learning happens at the level of graphics, touchscreens, what the educators like to call "manipulatives." The buildings themselves don't speak, don't teach, they merely house while complying with all requirements. There's little to be absorbed from experience and I doubt anyone will be drawing the plan, or mentally resting her cheek against the Tectum, 36 years on.

When Rafael Viñoly updated the Brooklyn Children's Museum, he added curvaceous shapes and primary colours to the outside, the better to signify child-like wonder. But inside the new rooms were boxy and plain, the better to accommodate a rotating series of exhibits and birthday parties. The architectural excitement is all decoration; the inside is a barn. By contrast, Cambridge Seven Associates's New England Aquarium, an exact contemporary of the King School, turns the reason why you go to an aquarium (to see the fish) into the organising principle for the building's architecture. It's also a box, but one textured at key points to indicate the ocean wonders inside; a box that leads you, tank by tank, on a scenographic journey from sea lions to penguins to more fish than you've ever seen in one place. All you have to do to experience the aquarium is walk, at your own pace, up the ramp that wraps a multi-story tank. No need for IMAX, no need to read (if you're under 6) the underwater experience is right there in the dark, intriguing space.

Playgrounds offer another journey from the specific to the generic. Susan G. Solomon's book American Playgrounds describes the high points of playground experimentation in the postwar period, from Richard Dattner's Adventure Playgrounds in Central Park (some recently restored and updated) to Isamu Noguchi's experiments with sculptural dreamscapes. Architects today are interested in making playgrounds again and many interesting experiments can be found in the book Playground Design by Michelle Galindo (2012). But Solomon describes a decade-by-decade constriction of spatial ambition as the result of fears over safety and budget. The model playground became a black, rubberised surface fitted with fixed, mass-produced equipment. You can see the same equipment, often made by Kompan, in Brooklyn and in Copenhagen. Where's the adventure in that? What's missing is loose parts, idiosyncratic parts, architecture that has ideas about learning and wants to help kids figure things out. Brooklyn Boulders, a growing chain of indoor climbing spaces for adults and children, seems to have hit on a contemporary formula at their sites in Brooklyn, Somerville and San Francisco.

What is at stake here not a question of Modernity (and indeed, not even all the Modern architecture historians in Cambridge got excited about saving the King School). Rather, it is respect for children as sensitive consumers of space. I read in the built work of Cambridge Seven Associates, Sert and Noguchi that children deserve the best design can give them, even if it might be scary for a moment (that dark aquarium) or strange until you climb it (those artificial mountains). The sanding down, the rounding off, the demolition of the obdurate, makes our children's worlds more boring places, places where all they can learn are the tasks we set them. Amy F. Ogata's recent book Designing the Creative Child describes the myriad ways middle-class ambitions are translated into the toys we buy and the spaces we make for kids inside our homes. But such ambitions also need to be translated into the public sphere.

Look again at the King School, structure laid bare. What better exercise than to say, "Here's a set of concrete floors and concrete columns, kids. What do you want to put in your new school?"

Alexandra Lange is a New York-based architecture and design critic. She is a Loeb Fellow at Harvard's Graduate School of Design for academic year 2013-2014 and is the author of Writing About Architecture: Mastering the Language of Buildings and Cities as well as the e-book The Dot-Com City: Silicon Valley Urbanism.