First there is the cliche: a young teacher, with little experience but big ambitions, wins over a classroom full of disengaged teenagers, introducing them to the wonders of education. Then there is the reality.

“I was very idealistic. I had dreams of coming in and making a difference,” said Laura Johnson. “But at the moment I’m just trying to get the pupils to learn information, to keep quiet and stay in their seats. No person with six weeks’ training is going to be brilliant straight away.”

The 24-year-old Oxford University graduate has just begun her first week as a geography teacher at Archbishop Lanfranc comprehensive, in the London borough of Croydon. She is one of the first cohort of graduates on Teach First. Based on an American initiative, Teach First is a fast-track training scheme for high-flying graduates. More than 180 graduates with degrees from top universities were given six weeks’ training in the summer, and then offered placements in London comprehensives.

The participants have undertaken to teach for two years, after which they will be fully qualified and can continue their careers in whatever direction they choose.

The programme includes a mini-MBA foundations in management course and participants should be well-placed for jobs with Teach First blue-chip sponsors, though the hope is that many will stay in the classroom. The first Teach First candidates began their school placements this September, so the past four weeks have been a crash course in classroom practicalities.

“I wanted to be an innovative teacher,” said Ms Johnson. “There were lots of crazy things I wanted to do. But now I just want the pupils to do their work.”

Simal Patel, a 21-year-old science teacher at Aylwin comprehensive, in Southwark, agrees. “I used to think that I was going to change the world and get As from everyone. Now I just want them to get a grade.

“But I do want to open their eyes to what’s out there, show them that maybe they could go on and do A-levels. Just putting that thought there is an achievement.”

Other elements of the job have also called for a rapid adjustment of preconceptions.

“All those things people say about teaching being a 9am to 3pm job are rubbish,” said Ms Patel, a graduate of King’s College, London. “In my first week I was working until midnight every day. It was a real shock.”

She had been used to organising her own time as a student. But as a new teacher, she has had to adjust to the rigidity of the school timetable, accepting that pupils, unlike university tutors, will not forgive a failure to be prepared for the lesson.

Robbie Walker, 22, who graduated from Oxford University this summer, agrees that managing his timetable has been the biggest challenge of his new job as a business studies teacher at West London Academy.

“You’ve got to be ultra-organised,” he said. “You’re not just organising yourself, but your students also. It’s very different to six months ago.”

But he says he has been able to adjust quickly to the demands of his new job.

“I find myself telling pupils to tuck their shirts in,” he says. “We all sit in the staffroom talking about kids we have problems with, and how we deal with them. Then you think, ‘Oh my God, I’m a teacher.’ ” Letters 29 www.teachfirst.org.uk