The boys' high school that struggled with low literacy and numeracy a decade ago is now one of the state's high achievers.
It now boasts outstanding HSC and Naplan results, principal Paul Sheather said.
"We have been the top comprehensive boys' school for four years and we have been placed 12th in the state for all comprehensive schools," Mr Sheather said.
The push to raise academic standards started with the arrival of the Mackellar Girls' former head of science eight years ago.
"I came to the school in 2008 with a vision around developing the curriculum so that it engaged boys in their learning," he said.
Shorter lessons, specific reading material and literacy scheduled at 10.40am for peak concentration, resulted in outstanding HSC English grades last year.
Half of the year's 40 advanced English students were awarded the top band.
"Twenty of our students received a band six and we were the best placed comprehensive school for HSC English ... not bad for a boys' school when girls have topped 70 per cent of HSC courses."
One gender difference refuses to go away, Mr Sheather said.
"Boys are languishing academically; girls are soaring. This trend has obvious implications not only for boys' intellectual development but for the national economy," he said.
With three boys of his own — the youngest is in Year 12 — he knows that boys flourish when lessons are fast-paced and non-sedentary.
"Girls can sit through an 80-minute lesson. Boys can't do this, so we changed the timetable. We have six 50-minute lessons," he said.
"Evidence suggests that fidgeting helps teen boys to focus. Movement helps boys engage both sides of their brain."