Too much teaching is "dull" and fails to challenge pupils, according to the chief inspector of schools.
Christine Gilbert said this week that inspectors would be spending more time observing lessons so they could give detailed recommendations on improving teaching standards.
Ms Gilbert's criticisms, made in her annual report, come despite the amount of teaching judged to be good or outstanding increasing over the past year.
In primary schools, almost two thirds of teaching falls in the top two categories, which is similar to a year ago.
In secondaries the proportion of good and outstanding teaching has increased from 52 per cent to 58 per cent. But the report said: "The proportions of inadequate teaching remain similar to last year's figures and too much teaching is still no better than satisfactory."
Ms Gilbert added: "Too much teaching is dull, lacking challenge and failing to engage pupils."
Inspections have shown that teachers feel pressure to put too much time into preparing children for tests, which restricts time available for other activities to interest and challenge pupils, the report said. The most successful schools manage to prepare pupils for tests without resorting to a narrow curriculum, it said.
Concerns have also been raised that some teachers do not have high enough expectations of students.