The proportion of NSW HSC students achieving band 6 in chemistry almost doubled and those achieving the top result in physics rose by 30 per cent when new syllabuses were tested for the first time last year.
Education chiefs and science teachers said the increase in top results did not mean the subjects had become easier, but rather the way the results were measured had changed.
Since 2010, the proportion of students achieving 90 or more out of 100 in chemistry had hovered between 10 and 13 per cent, before dropping below 10 per cent in the three years to 2018. Last year, it hit a decade high of 16.2 per cent.
In physics, 12.41 per cent of students achieved band 6, which was also a 10-year high. The only other time that percentage was in double figures was in 2017, when it hit 10.74 per cent. Biology results were consistent with previous years.