Lukas Sikes-Gerogiannis and peers prepare for their HSC chemistry exam. Credit:Ben Rushton The percentage of students studying advanced and intermediate maths also declined over a similar period but the proportion of students selecting entry-level maths grew by 60 per cent. John Kennedy, the lead author of the report and the head of science at St Andrew's Cathedral School in Sydney, said the downward trends had slowed but showed no sign of reversing and were "undoubtedly serious cause for concern". "No one really knows why it's happening, which I found rather disturbing," Mr Kennedy, whose report was published in Teaching Science: The Journal of the Australian Science Teachers Association, said.

Terry Lyons, a collaborator on the study with Frances Quinn, said previous research suggested the most likely cause of the decline was the smorgasbord of subjects final year students were now offered. At the same time science and mathematics participation had declined, physical education, business studies and VET subjects had increased in popularity, Dr Lyons, an associate professor of science education at Queensland University of Technology, said. He said the trend against studying final-year science and maths was concerning because it meant students might not have a sufficient grasp of scientific concepts that would help them understand important issues affecting society, such as climate change, GM crops and coal seam gas. "People who have a background in science beyond year 10 are more likely to persist in trying to understand [these issues] than someone who thinks, 'It's all too hard, I'm just going to go with what someone else says'," Dr Lyons said.

The decline in senior science participation could also lead to a deficit in the country's future scientific workforce, he said. A recent chief scientist's report stated that 75 per cent of the fastest growing occupations required science, technology, engineering or mathematics skills and knowledge. Dr Lyons said there were no easy solutions to the problem but teachers who were engaging and well-supported might help reserve participation rates. Mr Kennedy said engaging teachers helped spark a child's interest in science at a young age and helped retain older students in their final school years. "It's not that [students] find the sciences or the maths hard," said Mr Kennedy.

"If the teacher is engaging, wanting to work with the [student], then the [student] wanted to study it the next year," he said. Lukas Sikes-Gerogiannis, 17, who will sit HSC exams in intermediate maths and chemistry in the coming weeks, said he chose to carry on with year 12 chemistry because he found the subject stimulating and had performed well in junior school. "When you're studying an in-depth, content-heavy subject like that, you definitely need to be interested otherwise you're going to get lost," said the student from Sydney secondary college Blackwattle Bay campus. "I enjoyed maths as much as one can enjoy maths but I didn't know what I wanted to do [as a career] when I picked my subjects and figured it opened up the most avenues," he said. Research has found engaging children in science before the age of 11 to 14 was critical to their long-term interest in the subject.