Hyped-up teachers who feel under pressure and talk quickly in class are more likely to be effective.
The finding from Brian Apter, an educational psychologist for Wolverhampton council, challenges the accepted wisdom that talkative teachers put pupils off. It also suggests a stressed workforce may improve exam results.
Mr Apter observed more than 3,500 children and nearly 300 teachers in 141 primary classes and found that pupils tended to talk least when teachers talked most.
"During literacy and numeracy hours, teachers spend a lot of time speaking at a faster rate," he said. "They are pressing hard because it's really important to get the information into kids' heads. We thought that would exacerbate behaviour problems, but we were wrong. Teachers got much better behaviour when they put their foot on the pedal."
During these lessons, teachers tended to talk so urgently and quickly that pupils simply did not have time to misbehave. "Talk a lot and enthusiastically about your subject, motor around the classroom, engage kids all the time," he said. "They're the teachers who get good results and behaviour."
But it is not merely teachers' mouths that speed up under pressure. They become ultra-alert, with all senses in overdrive.
"A teacher who is driven by management to get the school up the league tables is an urgent teacher," said Mr Apter.
"So if children don't understand something, they'll pick up on it really quickly. The teacher wants every result in that class to be a good one."
Manufacturing this sense of urgency is not hard, teachers just need to psych themselves up. "Get the walk and the voice right," said Mr Apter. "Sound enthusiastic."
But he questions whether teachers should overdose on caffeine or obsess about their performance.
"It may be that this method is very good for cramming, but poor for getting deep, reflective knowledge about a subject," he said.
"One wonders what the toll is for teachers," he added. "You have to have the energy to be that full-on and hyped-up during literacy and numeracy hour.
"Then you come to the end of the day and collapse. I wonder whether this reflects all the teacher career-changers."
'If you stand and yap they switch off'
Nichola Hill prefers to describe herself as bubbly, rather than hyperactive. But her classes of Year 5 and 6 pupils at Scot Lane End Primary in Bolton, Lancashire, pay much greater attention when she talks quickly and urgently to them.
"They can tell it's important, so they listen more carefully," she said.
Ms Hill delivers short, speedy bursts of talk, interspersed with interactive activities.
"Pace is important. If a lesson is too slow, they switch off very quickly.
"If a person is bold with their body language, children respond. If you just stand and yap, they won't listen."
Not only does she have to race Y6 pupils through the curriculum before the May tests, but also conduct revision sessions.
"It's exhausting," said Ms Hill, 35. "Adrenaline keeps you going, but as soon as you have a break you switch off. This year, I was poorly at autumn half-term, Christmas and Easter.
"I can't imagine not being a teacher. But I can't imagine keeping this up for another 30 years either."