The number of 14 to 16-year-olds in further education and training is expected to double in the next eight years.
The expansion of part-time vocational programmes for school-age students has put extra strain on a workforce unaccustomed to teaching under-16s.
Helplines run by the sector skills council Lifelong Learning UK often receive calls from concerned staff who do not feel qualified to teach younger age-groups.
In response, Lifelong Learning UK has produced new support modules to help staff in colleges, work-based learning providers and community learning organisations who teach 14 to 16-year-olds.
"For career development purposes, many post-16 staff chose to work with older teenagers and adults," said John Clossick, LLUK's standards and qualifications manager. "Working with young learners from schools is a new experience. Many staff do not feel particularly equipped to deal with younger learners - with their individual learning needs and their behaviour."
Some FE colleges have a long tradition of collaborating with schools to offer vocational programmes. But in the past three years, government initiatives have brought a huge growth in the number of school pupils in colleges and work-based learning.
There are now about 120,000 under-16s in FE. One initiative, the Increased Flexibility Programme, works with partnerships of schools and colleges to offer a broader choice of subjects and qualifications, including vocational GCSEs and NVQs.
An evaluation conducted by the National Foundation for Educational Research found that the scheme had improved exam results, made young people more positive towards education and brought a 90 per cent staying-on rate post-16.
Following the Government's white paper, "14-19 Education and Skills", earlier this year, the number of school pupils going into colleges and work-based learning is set to increase to 240,000 by 2013, according to the Learning and Skills Council.
There are many good relationships between schools and colleges, but some lecturers believe schools are off-loading disaffected young people and those with behaviour issues on to colleges.
Postings on the TES website's online staffroom forum offer mixed views from FE staff on teaching pupils in Years 10 and 11.
One said: "I did a year of 14 to 16s. They were the most obnoxious, badly-behaved individuals I have ever come across. Instead of the schools sending those that would benefit from the FE environment, they sent those they wanted out of the way for a day."
Another reports a more positive experience, saying: "Generally, I enjoy teaching them. It's a change and they keep you on your toes."
Mr Clossick said: "If the overall 14-16 approach is going to have any meaning at all, then it's got to be across the total ability range. It should not just be for the disaffected and disengaged."
The new support materials from LLUK include modules on identifying learning needs and individual learning styles of 14 to 16-year-olds, curriculum planning and assessment.
There are also sections on the statutory and legal requirements relating to under-16s, qualifications and behaviour management as well as teaching and training methods to motivate pupils.
Fourteen to 16 education will also form part of new qualifications for the sector. LLUK is drafting new standards that will see new staff working towards Qualified Teacher Learning and Skills status.
Karen Murray, senior policy manager for 14-19 education at the Learning and Skills Council, disagrees with the perception that some colleges are being treated as dumping grounds.
"These programmes are absolutely not about disaffected young people being dumped on colleges," she said.
Ms Murray said one of the critical factors in successful collaboration between schools and colleges is to have the right staff teaching under-16s.
She added: "If the staff involved went into FE to get away from school or not to teach school-aged children, then clearly they're not the right people to persuade to be involved in pre-16 activity.
"But where there are fantastic enthusiasts and almost evangelical staff who see this as a fantastic opportunity - and there are many of them - it works really well."
The new support modules for working with young students can be downloaded from the Lifelong Learning UK website: For details see: www.lifelonglearninguk.org