Some second-level school children are getting more than 100 extra hours of maths tuition than others, a new study reveals.
The amount of time teenage students spend in maths classes varies hugely depending on the school they attend and the class they are in.
Some students receive as much as 26pc less maths tuition than others over the course of their time in post-primary school.
The "substantial inequity" in the maths instruction time between schools, and even between classes in the same school, is highlighted in a new report.
Researchers found that teenagers are timetabled for maths classes for an average of 106 hours for first years, up to 128 hours for 'honours' students in sixth year.
But some first years are timetabled for only 67 hours a year for maths, rising as high as 167 hours a year in other schools.
Over the three years of Junior Cycle, there are schools in which students receive 401 hours' maths tuition, while for others it is a low of 242 hours.
At senior cycle, time for maths varies from 100 hours to 161 hours a year between schools - which means a cumulative difference of 122 hours over the two years.
The differences result in substantial variations when a student studies maths from first year to sixth year in different schools.
While some receive a total of 659 hours maths tuition over a five-year period, at the other end of the spectrum it is 26pc less, at 487 hours.
"A small increase in time allocation can have a positive effect on student achievement," said report co-author Dr Niamh O'Meara of EPI-Stem, the National Centre for Science, Teaching, Engineering and Maths (STEM) Education.
The study, the first in time allocation for maths in Irish second-level schools, was co- authored by Dr Mark Prendergast, associate professor at the School of Education, Trinity College Dublin. It is published in the latest issue of 'Irish Educational Studies'.
On average, Irish post- primary schools devote the same amount of school time to maths tuition as other countries.
But the report authors are worried about wide variations which leave some pupils getting a lot less attention in the subject.
"Second-level students in Ireland, regardless of the school, are studying the same syllabi and prepared for the same State examinations, and there is no argument to support the variation in instruction time evident in the results of the study," they state.
The report authors are also concerned about the number of hours of timetabled maths classes that don't actually take place because of interruptions, such as the mock exams.
Overall, between, 6pc-9pc of timetabled junior cycle maths class don't happen, while at senior cycle it is 5pc-8pc. The higher drop-offs come in third year and sixth year, when the "mocks" take place.
Second-level schools are free to decide how to allocate time for different subjects, although the Department of Education recommends, 3.3 hours a week, about 111 hours a year, for maths.
Commenting on the tendency for lower time allocations for younger students, the authors say less exposure to maths over a number of years could mean that they enter senior cycle without ever having time to explore new concepts and develop a sound understanding of the subject.
Despite concerns about the variations between schools, and timetabled classes that don't happen, the authors do acknowledge that throwing more time at the subject is not always the answer - but it is important how that time is used.