There is mounting evidence that lecturers are having difficulty coping with the demands of "increased flexibility", the Government's programme which puts 14 to 16 year-olds in colleges.
A survey by Natfhe, the lecturers' union, has shown that staff worry most about children being disruptive.
Research by Grimsby's institute of further and higher education found that 86 per cent felt they had no choice about teaching the under-16s, though 81 per cent were not qualified to do so. Where training had been provided, most found it to be inadequate.
"I feel the whole issue is a time bomb," said one respondent. "I have 25 years' teaching experience, but often feel inadequate and useless.
Sometimes I do fear for my own safety.
"We are not always informed of the learner's background, which often includes violent behaviour, aggression, drug-taking and assaults on teaching staff. Support is an essential issue and it is mostly wholly inadequate."
Another wrote: "Working with 14 to 16-year-olds brought a whole load of different problems, but among the biggest problem is discipline and control.
"Classes were large, and with semi-vocational subjects it became a nightmare to supervise. Also, lack of interest by students and constant disruptions completely destroyed any learning by the group."
The union says the college is responding positively to lecturers' concerns, but it suspects that the problem is echoed across the country.
John Giddins, regional official for Yorkshire and Humberside, said Grimsby institute is responding well to concerns raised in the survey, "I used to teach in school before further education and they had systems which removed troublesome students from class in order to get on with teaching and learning for the rest," he said. "We don't have that in FE.
"We welcome widening participation and opportunities for young people, so we're not saying this shouldn't happen. What we're saying is that there have to be proper systems put in place."
A college spokesman said: "We have had success getting Year 11 students re-engaged with education to the extent that 40 of the 49 students (from last year) have returned to continue their studies. We have and will continue to provide staff with training for the students' needs."
The Department for Education and Skills introduced the increased flexibility programme in 2002 with the aim of opening up vocational education for pupils at key stage 4.
At present, about 100,000 pupils in England spend part of their school week in college, and the initiative has led to more 16-year-olds choosing to stay in education.
The evidence from Natfhe's survey - albeit from one college - will bolster the case of those who suggest that FE has become a dumping ground.
A survey of FE colleges by the Learning and Skills Development Agency last year found that more than half of the largest 18 colleges cited badly-behaved teenagers as a "major concern".
Helplines run by the FE sector skills council, Lifelong Learning UK, frequently get calls from concerned staff who feel unqualified to teach younger students.
LLUK has produced support modules for FE staff which include behaviour management. It emphasises that, because of duty-of-care requirements, staff cannot send 14 to 16-year-olds out of a classroom if they are unsupervised.
Managers should ensure that there is a clear code of conduct, with consequences made clear if that code is broken.
They need to support staff by sharing best practice, and by making supervision arrangements if young people do have to be removed from a classroom or workshop.
Croydon college is part of the South London Learning Partnership, which is made up of schools, colleges and work-based learning providers across six London boroughs.
John Stopani, head of community care at the college, said it lays down clear parameters for14 to 16-year-olds. "The big difference with this age group in a college environment is that you need to be very clear about what the guidelines are and what the parameters are," he said.
Knowsley college in Merseyside, which was an early provider of courses for 14 to 16-year-olds before the term "increased flexibility" was coined, says its own approach has been effective.
Principal Sir George Sweeney said the college's under-16s are no different from its traditional age group. "What you have to do is make sure that (these students) understand the framework within which they are in a college, and they do," he said. "They are no more difficult than 16 to 18-year-olds in that respect."
Over the coming months, FE Focus will run a series of occasional articles to help lecturers overcome their common concerns about teaching 14 to 16-year-olds. If there are any particular areas you would like us to look at, please email: firstname.lastname@example.org