South Australian Paralympic gold medallist Brayden Davidson has defied childhood bullies to prove he is one of the best sports stars in the world.

The 18-year-old long jumper, who was born with cerebral palsy, was repeatedly told as a child he did not have what it took to be an athlete.

But on Tuesday, hundreds of senior students at Reynella East College celebrated the gold medal achievement of the former student.

Students and teachers cheered as a replay of Davidson’s winning jump was aired during a special assembly.

Davidson’s mum, Gail, wiped away tears as she watched on.

“He loved sport but he hated sports days because he was never fast enough, never strong enough,” she said.

“We had belief in him to do it.”

After one particularly bad day at school as a six-year-old, he retreated to his late grandparents’ house where his dream to become a Paralympian was sparked.

“He was always last to be picked for a team … and when you’re told that so many times, he was really flat,” Mrs Davidson said.

“And [his grandma] said to him ‘look you’ve got a disability, the Paralympics that’s what you can do’.

“If you dare to dream, it can come true.”

Davidson defied all odds, and a groin injury, to jump of 5.62 metres to clinch gold in Rio. The jump was 11 centimetres better than his previous best and broke a Paralympic record.

Davidson’s family watched a replay of his gold-medal winning jump at a special assembly.

Sister and Year 9 student Vashti Davidson described her brother as a humble person who deserved to be celebrated.

“I think proud is probably an understatement,” she said.

“If there was a word 10 times better than proud, that’d be it.

“He’s such a strong person, even in the way he carries himself and his sportsmanship.”

Despite Davidson’s success, his journey to becoming a Paralympian has not all gone to plan.

His dream was to become a swimmer but his cerebral palsy makes the muscles in his shoulders too tight.

A coach told him he could not modify the strokes so he quickly lost his passion for swimming.

But just four weeks after taking up long jump about six years ago, Davidson was competing at his first junior national competition and his love for the sport has stuck.

–ABC