The merits and demerits of having third-level students sit exams more than once a year will be the subject of a conference to be held in Dublin Castle tomorrow. The conference, which is organised by the Union of Students in Ireland (USI), will feature student representatives past and present and speakers from the Department of Education, the National Council for Education Awards, the teachers' unions and colleges at home and abroad.

Darren McCallig, education officer with USI, says that while semesterisation has been introduced to virtually every third-level institution in the State, the results have been mixed and the model will not necessarily be introduced in every course.

"One of the aims of the conference is to encourage a dialogue on best practice in introducing and running a semesterised exam system.

"Semesterisation is part of an effort to link in with European systems, which are largely modularised. The theory is that it's better for students because it means five or six days in May or June aren't the sole determinant of your results. "The Green Paper on Adult Education has even looked at it as a method of having students enter college at different times of the year.

"However, the semsterised year has been implemented with varying degrees of success in different colleges. New institutes of technology which have implemented it from the start have had the fewest problems, but some of the more established colleges have had to switch model from year to year.

"A lot of difficulties hinge around the amount of time students have to prepare for their Christmas exams. There are also problems with college facilities. In theory, having two sets of exams eases the summer rush to use the library and the computers - but in practice it means they're busy all year round.

"Semesterisation also creates problems for students' unions and clubs and societies. Our main bugbear is that it makes college a much more academic exercise: there's less time for extra-curricular activities - and that's having a noticeable effect on college social life."

Students' summer earning potential can also be reduced by the introduction of a second set of exams. "If you're going to have exams before Christmas you have to start very early in September, and to have a second set requires pushing term late into summer. That reduces the amount of time students get for their summer holidays."

Tomorrow's conference will be opened by Paddy McDonagh, the director of higher education in the Department of Education and Science. The registrars of Dublin City University and Tallaght Institute of Technolgy will give differing Irish perspectives on the introduction of semesterisation, while Dr Gaie Davidson-Burnet of UCAS and Dr Norman Philip Fletcher of Loughborough University will describe the British experience of dividing the college year. Former USI officer Malcolm Byrne, who led a student protest in UCD in 1994 at the way in which semesterisation was introduced to Belfield, will address the conference on the impact of semesterisation on students.