Warning: This story contains details that may distress some readers.

The operators of the jumping castle used at Hillcrest Primary School when six students died in 2021 used YouTube to research how to operate jumping castles, a Tasmanian court has heard. 

Six students — Zane Mellor, Peter Dodt, Jalailah Jayne-Maree Jones, Addison Stewart, Jye Sheehan and Chace Harrison — died in the 2021 incident, and three of their classmates were seriously injured.

Devonport Magistrates Court has heard a "mini tornado" swept through the grounds of the primary school at its end-of-year celebrations on December 16, 2021, and pulled a jumping castle and inflatable zorb balls up to 20 metres into the air.

Rosemary Anne Gamble from Taz-Zorb, who supplied the inflatables, has pleaded not guilty to the charge of failure to comply with health and safety duties.

Much of the case has centred around how the jumping castle was anchored to the ground.

Ms Gamble's partner, Robert Monte, told the court he was present when she purchased the jumping castle from Chinese company East Inflatables in November 2015.

Giving evidence on Thursday, Mr Monte said he was there when the jumping castle was delivered, and that he and Ms Gamble were "self-taught" inflatables operators.

He said the castle was delivered with four 30cm pegs, and no instruction manual.

"We did a lot of YouTube searching, watching other people … how they set up castles," he said when Ms Wilson asked if they had any formal training.

Mr Monte said that on the day of the tragedy he had pegged down one side of the jumping castle and another Taz-Zorb worker, Jesse Barrett, had pegged down the other side.

Monte only realised something was wrong after jumping castle took off 

He said four pegs were used to anchor the castle, which he understood to be the bare minimum, and that the weather was fine on the day.

Mr Monte said he was operating the zorb balls that day while Ms Gamble was running the castle.

He only became aware that something was wrong when he looked up and saw the jumping castle in the air, he said.

"It was already in the air when I saw it," Mr Monte said, adding that the inflatable border for the zorb ball arena also became airborne at about the same time.

"Halfway across the field I got knocked down by the border. The border came down and hit me.

"I went down to try and help the kids."

Crown prosecutor Madeleine Wilson SC clarified whether he began tending "to the injured and dying children", and he replied: "Yes."

The parents and families of the victims were sitting in the rear of the court while Mr Monte spoke, and several became visibly upset while he gave his evidence.

One father stormed out of the court saying "you're f***ing joking" as he left, while a mother caressed the face of another mother as she cried.

Decision in court case may not be made until next year

The summing up of the case against Ms Gamble and a verdict may not be made until next year, the court heard earlier.

Defence lawyer Chris Dockray SC and prosecutor Ms Wilson discussed with Magistrate Robert Webster how they expected the case to proceed.

The lawyers agreed it was unlikely they would each be ready to make their closing submissions to Mr Webster at the end of the two weeks of hearings, and that, due to other commitments, they may not be able to schedule an appropriate time during 2024.

Mr Webster agreed with Ms Wilson that due to the significant public interest in the case it was important to prioritise it, but indicated the parties must also take the time necessary to properly make their arguments.

The case is likely to continue, therefore, beyond the third anniversary of the tragedy on December 16, 2024 and into 2025.

3D render of jumping castle made

So far, the hearing has centred on forensic evidence from Tasmania Police Constable Dean Wotherspoon, who was a first responder.

It has also heard from East Inflatables, the Chinese company that sold the jumping castle to Ms Gamble in 2015.

On Thursday morning, Constable Wotherspoon's evidence concluded with further forensic photos of aspects of the inflatables and accessories.

He also discussed a 3D render of the reinflated jumping castle and zorb balls made in August this year, which was created when defence expert witnesses were conducting examinations.

Ms Wilson asked Constable Wotherspoon about the time taken to make those assessments.

"It certainly took longer to set up and pack up than the inspection took," Constable Wotherspoon said.

The case is likely to be further investigated in a coronial inquest by coroner Olivia McTaggart at a later date.

The inquest was scheduled for 2023, but the current criminal charge by WorkSafe Tasmania was given priority.