Some are laughing as they come through the school gates. Some are frowning. More are shivering. It's another school day in January, just coming up to 8.30am. The students and teachers of Colaiste de hIde, an all-Irish second-level school in Tallaght, Co Dublin, are making their way to their classrooms. When the bell rings, the great migration of teenagers weaves once again through the corridors. The day is under way in Colaiste de hIde.

Eamonn O Dochartaigh, who teaches Junior Cert science, jokes with some of the students as he walks to the science room. "Bim faoi bhru ag tus an lae ag ullmhu rudai," deir se. "Bim anghnothach sula thosaionn na ranganna, caithfidh tu gach rud a bheith reidh. Ansin bim ag caint le daoine ag suil isteach, ag magadh le daoine. An chead rud a deirim nuair a theim isteach is docha na `togaigi amach na leabhair' agus ansin deanaim marcail ar na rolai."

Generally he tries to find out what the students think about whatever he's going to talk about . . . "if you start from what they know, it links you up with them. Otherwise you're not connecting with them."

O Dochartaigh sees teaching moving in a different direction. "It's very dificult to get young people to accept the old rigid, traditional form of classroom control. Quite a lot of teachers like myself are happy to see that change and to move towards new ways of working with young people, ways that are less confrontational and more productive."

The key to being an effective teacher, he believes, is that you "need to be less rigid, more open, less defensive, able to listen to the kids". Over the years, his style of teaching has changed as he has changed. "You have to be developing as a person. It's very, very rewarding as a job."

At the moment the class is learning about light. They have just finished learning all about pollination. "I love teaching," he says. "I just really enjoy the crack with the pupils. It can be really wonderful, especially times when it's going well, it's magic." He also teachers technology and environment to the Transition Year class.

The college is just five years old. It has up to 200 students, 14 teachers and is getting bigger each year. O Dochartaigh, whose degree from TCD is in theoretical physics, taught in a number of Dublin schools before he moved here.

His first teaching job was in inner city London. He had a class of about 20, aged between 15 and 16. "It was pretty mad," he recalls. "I had a class that was really wild. It was a bit stressful. I was just out of college. They were good kids but really, really wild. They came from a very poor black community in Clapham. They had huge problems."

O Dochartaigh grew up in Belfast. He went to Edmund Rice Primary School and then attended St Malachy's College between 1971 and 1978. After sitting his A-levels, he left to do a four-year honours degree course in Dublin. After four years, plus a two-year stint working with the university's students' union, he graduated.

He then went north again, primarily because he was awarded a grant, to complete a post-graduate certificate in education at Queens. "They had quite a good system in terms of subject assessment and practical examples, including how to structure classes . . . it was all about structuring knowledge."

Later, because he did not complete the H Dip in Education, he had to apply to the Registration Council when he returned from London so that he could get official recognition in the Republic as a teacher. "They really scrutinise all your qualifications. I eventually got registered. I had to attend a series of lectures in TCD on the history of Irish education over the course of a term and then write an essay at the end."

He then spent three years in Senior College, Ballyfermot, teaching physics and engineering to PLC classes. After that he taught in O'Connell's CBS on North Richmond Street, Dublin.

At the moment, he is availing of a job-share which is becoming more common, he says. "Ta na paisti og agus bhi me ag iarraidh a bheith sa bhaile leo," arsa se.

"The real challenge of teaching is the relationship that your form with a group of young people. Often that's what you're not prepared for. And then when you're not prepared you act according to the model that you know, you act like the teachers you knew.

"It's a two-way process. For me it's about giving them access to the right learning experience. You can't go in with a rigid attitude."