In Japan, the traditional respect for teachers seems to be breaking down. A recent survey of primary and elementary school teachers found that 44% had witnessed "collapsed classes".

Watch Juliet Hindell's report on the education system in crisis

Teachers said they did not know how to cope with unruly and inattentive pupils and said it was impossible to teach them. The education system which was once the envy of the world is facing a crisis.

Hiroo Shiga, a 50-year-old primary school teacher has never seen anything as bad in his 30 years in the profession.

"Kids talk back, they sit in class openly reading books which aren't the textbook and walk out of class when they feel like it. Once a group of boys started playing ball in the back of the class while the teacher was teaching," he said.

Children spend too long playing computer games on their own

These may seem like minor infractions of school discipline by international standards, but in Japan such behaviour is unheard of. Respect for education, schools and teachers has until now been very high. But educators and parents say that classes have become increasingly chaotic in the last few years.

Masao Asami found out about his son's disrupted class from another parent. The boy, then 12 years old, was singled out as a troublemaker but Mr Asami thinks the teachers were equally at fault.

"In my son's class the kids would insult the teacher and shout. Once they threw knives at each other and chucked plates out of the window," he said.

The teacher ignored the situation and pretended not to notice. The troublemakers in turn ignored her too.

Juliet Hindell: "It is proving a sharp learning curve"

Mr Shiga says the Japanese system under which a teacher taught a class of 40 to 50 pupils and they listened obediently is no longer viable. He says parents also no longer respect the schools, doing such things as taking their children on holiday during term time.

Kazuko Narui, a teacher and education consultant, agrees that parents share much of the blame. She says nowadays children spend too much time on their own playing computer games.

They arrive at school without knowing the most basic rules of good behaviour. "They used to learn the rules by living in a close-knit community where they played outside and had older children looking after them, now they have no guidance," she said.

She and other experts believe that part of the problem is that Japan is changing from a group-oriented society to an individualistic one. The system has yet to catch up with the times.

"You can't expect teachers who've always taught big groups to suddenly know how to cope with rowdy individuals," she said.

Teacher stabbed to death by her 13 year old pupil

There has long been a problem with unruly older children in Japan. Last year, a 13-year-old stabbed his teacher to death because she told him off for being late. The incident sparked a debate about violence and knives in schools. But the fear now is that problems are starting at a much younger age.

Hiroo Shiga says the lack of discipline is taking its toll on teaching staff. Newcomers and veterans alike are stressed out, and half the sick days teachers took last year were for stress-related illness.

He says teachers feel they are losing control of their classes and can no longer teach.