There are wide variations in the quality of education in English primary schools, a major study has found.
Study found the extent of group and whole-class working varied
Teaching and behaviour was worse in schools with pupils from disadvantaged backgrounds, researchers said.
The report for the DfES listed detailed observations in 125 Year 5 classes. It found most teachers followed the national literacy and maths strategies.
However, nearly half the lessons had no "plenary" session, in which the whole class discussed what had been learnt.
Despite evidence of rising standards in schools, quality remained uneven, said the researchers from the universities of London, Oxford and Nottingham, working for the Department for Education and Skills.
Their findings echo concerns from the inspectorate, Ofsted, about the gulf between the best and worst schools.
Pupils in different Year 5 classes can have quite different educational experiences
"The extent of the variation indicates that pupils in different Year 5 classes can have quite different educational experiences," the report said.
Children got little feedback in a fifth of classes and 17% had very low ratings for "richness of instruction".
Those pupils had "poorer learning environments" as a result.
More time was spent on whole class work (56%) than individual work (36%) and group work was uncommon (9%) although other research has suggested it can have benefits.
A plenary session is recommended in the national teaching strategies but was observed in only a third of classes in both literacy and numeracy.
In about a quarter of them it was not seen in either subject.
The quality of teaching was "significantly higher" where a plenary was used and was lowest where it was absent.
The researchers said its absence was "of particular concern" as it was intended to provide a chance for feedback that could raise standards.
The problem might be teachers' lack of awareness of its purpose, or the fact that earlier parts of the lesson had overrun because their organisation was weak.
Schools in poorer areas exhibited poorer teaching.
And they had less of what the researchers called "social support for learning" - with everyone's contribution being taken seriously and pupils' errors being used as learning opportunities.
"This may reflect lower expectations, difficulties in recruiting/retaining good/experienced teachers and the greater behavioural difficulties associated with teaching in more challenging contexts," the report said.
Disruptive behaviour and negative or "chaotic" classroom atmospheres were likely to coincide - though it was not clear whether a chaotic atmosphere produced disruptive behaviour or was caused by it.
"It seems likely that the two tend to reinforce each other."
In a separate report from the same long-term study of some 2,500 children, the researchers said pupils' attainment at the age of about seven (KS1) was a powerful predictor of their performance when they left primary school.
Those eligible for free school meals and those with special educational needs showed "substantially less progress" across all subjects.
"As these pupils also have lower KS1 attainment, the gap is widening between them and others over time."
A spokesman for the Department for Education and Skills said the report demonstrated that the lesson model advocated by the government's primary national strategy was effective.
Standards had never been higher.
"Our Primary National Strategy and the work of thousands of teachers have enabled around 95,000 more 11-year-olds to master literacy and 83,000 more to master numeracy this year than did in 1997," he said.
Schools that had used its approach, including a plenary at the end, had significantly higher teaching quality, "something our guidance to schools makes clear".
DfES: Variations in teacher and pupil behaviours in Year 5 classes and The effectiveness of primary schools in England in Key Stage 2 for 2002, 2003 and 2004, by Edward Melhuish and Helena Romaniuk, Birkbeck, University of London; Pam Sammons, University of Nottingham; Kathy Sylva, University of Oxford; Iram Siraj-Blatchford and Brenda Taggart, Institute of Education, University of London.