BY DAY, mathematics teacher Lim Yueh Fong of Serangoon Junior College put in extra hours to give remedial classes to her students.

By night, she clocked irregular hours of sleep because she was breastfeeding her now nine- month-old son Kiran.

When she fell ill from trying to do it all, the 36-year-old mother of two knew something had to give.

Last July, she gave up half her workload at school and went on the part-time teaching scheme.

Since then, for proportionately less pay, she has to be in school only four out of five days a week.

And because those nightly feeds mean she cannot rise early enough, the school has tweaked her timetable so that her classes start no earlier than 10am and end by 3pm.

Ms Caroline Anne Yeow, the vice-principal at the JC, which has six part-time teachers, said: 'We try our best to accommodate them as we want to keep talent.'

Like Mrs Lim, more teachers are choosing to take on a lighter load, mostly so they can handle child care. The number of part-timers has jumped from 120 in 2004 to 310 in this new school year.

A Ministry of Education (MOE) spokesman said the rise in numbers is partly a result of the extension of the scheme for married teachers with children.

Where previously, only married female teachers with children aged under six were eligible, the scheme - also for those aged 55 and up seeking part-time jobs - is now open to those with kids under 12.

With 310 part-time teachers spread out among at least 360 primary and secondary schools and junior colleges - with a total of about 28,000 teachers - part-timers are still a relatively rare breed.

But the numbers will rise because MOE is adding five full-time teacher posts to each of the 28 school clusters to support schools with part-time teachers.

It will also let senior personnel, including heads of department and master teachers - senior teachers in the school - take the part-time route.

A part-time teacher's workload will depend on what is agreed with the principal.

Some teachers ask to be exempted from taking care of co-curricular activities or committee work; others may take on such duties, but teach fewer classes.

Demand for such arrangements has risen, now that the median age among teachers is 32, when most would have young families.

But having part-time teachers on board puts a strain on timetables and manpower, say teachers and principals interviewed.

Other teachers also have to be understanding.

At Chung Cheng High School (Main), for example, full-time teachers have to take over when any of the seven part-timers are not around.

Its principal Lo Chee Lin said: 'There needs to be a lot of team work and understanding among the staff.'

Serangoon JC's Mrs Lim said the part-time scheme helps retain teachers, who may otherwise take no-pay leave or quit.

'It helps us keep in touch with teaching, especially with the new syllabus.'