About 75 per cent of students in years 7 to 10 are already being taught maths for at least one year by a teacher not trained in the subject area and the situation is set to worsen,with an expected 650,000 extra students across the country by 2026.
The report's co-author Jan Thomas,a senior fellow at AMSI,said programs to retrain existing teachers in maths are long overdue and are now likely the only way left to address the shortage.
"In 1987,when I was a research officer for a Victorian government study,we picked up that there was an emerging problem there. I still remember the shock I got when we realised the way schools were coping was to reduce maths classes from 240 minutes to 200 minutes,"Ms Thomas said.
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"From the 1980s,we've known that unless we did something there were going to be more out-of-field teachers,and that's exactly what happened.
"It's now past when the government should have done something and the only way we can get more qualified teachers into schools quickly is to retrain existing teachers in other areas who are already being asked to teach maths."
Ms Thomas said any successful programs would need to be broken into small,flexible units that could be combined to make up a qualification and be completed during breaks in teaching periods.