, says NZ educators are deluded in thinking teachers should let children direct what they want to learn about.
It calls for a much more detailed curriculum specifying what children should learn at each level, and standardised national assessments to ensure they learn those things.
But Kiwi experts have hit back at the findings, saying prescriptive "Eurocentric" teaching practices risk ignoring the needs of indigenous communities.
Report author Briar Lipson, a former British maths teacher who helped set up two charitable low-decile primary schools in London, says encouraging children to choose what they want to learn entrenches the differences that children start school with.
"It's too much of a lottery," she says.
"Students of unabridged Shakespeare are judged equally to those who study the lyrics of 'more relevant' artists like Tupac or David Bowie.
"Such deference to relevance explains why the NZ Curriculum exacerbates variations between classrooms and schools. Rather than having a narrowing effect, it intensifies inequity."
Lipson says New Zealand's educational outcomes have declined in parallel with the rise of child-led learning.
In social studies, for example, children in senior primary school are now expected to "understand how people view and use places differently", as well as a more specific "understand how early Polynesian and British migrations to New Zealand have continuing significance for tangata whenua and communities".
Children are expected to learn these often-vague topics through their own "inquiry".
"Children might use the internet to research a topic, then report their findings to the class," Lipson writes.
She says this approach may work for children who already know something about the topic, but not for those who don't know where to start. She cites Professor John Hattie's research showing that inquiry-based teaching has an effect size that is far below direct instruction.
However Hattie, a former Auckland University professor now based in Melbourne, says there is "not one iota of evidence that NZ has slipped in the international assessments because it has adopted a child-centred philosophy".
"I have often lauded the NZ curriculum because (unlike the Australian one at about 2500 pages) it is brief (67 pages), it allows multiple opportunities for schools to choose the specifics ...
it is rich in knowledge and invites a balanced approach to precious knowledge and competencies,"
Albany Senior High School principal Claire Amos says Lipson's view that the curriculum should prescribe Shakespeare rather than Tupac or Bowie is "Eurocentric".
"The danger of prescribing a powerful knowledge curriculum is about whose knowledge.
"This is really a colonial tool of putting old western knowledge ahead of indigenous communities."
Auckland primary school teacher Mark Bracey, who blogs at Ease Education, says teachers need to find the "sweet spot" that is "teacher-led, student-sensitive".
"I am the benign dictator, so it's very much teacher-directed. I set up the framework for our learning engagement, and I have high expectations," he says.
"But at some point, when you get that instructional component right, the students take some ownership of what they are learning. They go, 'Ah, I get it, I just have to do this'.
"So what I see is really collegial learning, so I become more of a conductor, but I am totally understanding every individual child and I'm pushing them and prodding them. So it's not either/or."
Learning the rules
When Jean Batten School began teaching the structure of the English language, even the teachers learned things that no one had taught them when they were at school.
The Māngere decile-1, mainly Pasifika school is working with Dr Alexis Siteine from Auckland University's Knowledge and Education Research Unit to develop a "knowledge-rich" curriculum for writing.
It's happening purely by chance. The school's principal Nardi Leonard, a former NZ women's softball captain and keen basketballer, ran into Siteine on the sidelines of a basketball game.
"We just started talking, and she talked about the Knowledge-Rich Schools Project," says Leonard.
"For us at the time, for the amount of effort that we were putting into developing literacy, we just felt the payback was minimal, our movement had been minimal.
"So it was like, if you keep doing the same thing you're going to get the same results, so we needed to try something different."
Siteine says: "The teachers said to me, 'Oh, the kids can't write a sentence.' That came as no surprise to me because some of my postgraduate students were the same."
They had been teaching the kids how to write a sentence, but Siteine realised that the teachers themselves didn't know the elements that made up a sentence.
"So we decided to make it really explicit," she says.
"So we taught sentence syntax, and we taught the subject-verb-object form of the sentence.
"We taught the students those concepts of subject, verb, object, and what the verb does to the object and the parts of speech associated with that."
The research unit, led by Professor Elizabeth Rata, believes that teaching coherent knowledge starts with identifying the key "concepts" or "meaning" of a topic, then choosing the content that illustrates those concepts, and only then teaching the "how-to" skills.
In this case, the "how-to" of writing stemmed from deep understanding of the rules of English.
Leonard says it highlighted gaps in the teachers' own knowledge.
"If they don't understand the richness of the language, then how are they going to teach it?" she asks.
"For us, it was about encouraging our students to not just write in a rich manner, but to verbalise - to get away from one-word answers and to be really quite eloquent about what they are talking about."