The ambulance arrived at The Gordon Schools in Huntly in 10 minutes - but the young maths teacher knew there was something seriously wrong when he couldn't move his legs.
Dave Henderson was a qualified trampoline coach, a boyish, sporty all- rounder, always looking for new challenges. He'd been demonstrating a move on the trampoline at an after-school club in the school gym when the accident happened.
Afterwards he would remember how everything seemed to go in slow motion when he landed on the back of his neck on the trampoline - he knew immediately he had broken his neck.
The 33-year-old father of four was airlifted from hospital in Elgin to the spinal injuries unit at the Southern General Hospital in Glasgow in October 2007.
For the first three months he lay paralysed, fighting for his life. By the time school was breaking up for summer eight months later, he was well enough to go home to his young family.
Dave's wife Mairi is a teacher too but works at home now, looking after their four children: Rebecca, 12, Sam, 10, Kirsten, 8, and Eilidh, 6. She also helps look after her sister's two young children.
Today, Mr Henderson is back in school teaching a second-year maths class from his wheelchair. This afternoon they're learning about circles. Thirteen-year-old Ian Webster was at primary school when Mr Henderson was injured, but remembers the story from the news. "It's good to have him back, because he's a really good teacher," Ian whispers, as he copies diagrams diligently into his jotter.
In an interview with The TESS a year after the accident, Dave spoke about his determination to get back to the classroom. He's been back for six weeks now - one day a week in school and a day at home doing preparation. He visited the Aberdeenshire school regularly on an informal basis last year, to see how things would work on his return and re-acquaint himself with colleagues and pupils. His comeback has been a gradual process, allowing him to familiarise himself with the lie of the land before his formal return to the classroom.
"I really enjoy teaching - it's good to be back," he grins. "It's good just to get back into the environment. Being at home most of the time is not actually healthy for you - the interaction with the kids is really good. I'm just glad to be back doing something that's useful for the department."
About a year after the accident, Dave recovered some movement in his arm and can now scratch his face with one hand and push up his specs. It's not enough to allow him to drink or feed himself or point to the board, but he has a personal assistant, Emily Phillips, to help him manage in the class and around the school.
His maths class goes like clockwork and he talks them through the diagrams on the PowerPoint behind him. Emily operates the PowerPoint and walks round to check pupils are up to speed.
Emily was the family's 16-year-old babysitter and a fifth-year pupil at this school when Dave was injured. She and a friend visited "Mr H" in hospital and helped look after him when he got home.
She's now employed as a part-time assistant when she comes home from college in Glasgow. Emily anticipates everything Dave needs in the classroom and feeds him soup and a sandwich in the lunch break.
Nurses, carers and physios troop in and out of the Henderson household on a daily basis. But on the day he's teaching, Emily gets him up and organised and into school on time. "I can't get carers or nurses to match that, because the nurses don't start until half eight," Dave explains.
"She really has a dual role as classroom assistant and carer because she is doing both roles," says Dave. "Her main thing is making sure all the practical needs are met; she checks basic things but also assists round the classroom, putting out materials, gathering things in, writing on the board sometimes.
"She's a bit of a livewire and she knows a lot of the children as well, which has changed the dynamics a wee bit for me because I get a little bit more insight into some of the things that are going on because she knows the kids and she's got connections," he smiles.
Colleagues such as his former tennis partner Ellie Ingram, the maths PT, are practical and supportive.
"It's good fun again," says Ellie, who appreciates his dry sense of humour and positive outlook. She's working alongside him, sitting in on classes to see how it's going and suggesting ideas to overcome difficulties.
"Pupils are adapting to his way of teaching by going to him for help when needed. They write on the whiteboard and Dave uses mini whiteboards frequently to check that they've all understood," says Mrs Ingram.
At the moment Mr Henderson teaches one class of second years, a group from another second year and a group of Mrs Ingram's Intermediate 2 classes.
"We're gradually increasing the amount of time with classes," she says.
He can use a voice-activated laptop for class work, but at the moment Dave prefers to use a "head mouse" which links to the projector, with the lesson based around the PowerPoint.
"When I am teaching, if I am doing three periods within the day, I find I am quite tired. But the stamina is building towards that and generally the health is very good," says Mr Henderson. "Of course I'm heading towards the 40 mark now," he jokes, but he's still a few years away from that milestone.
Ask Dave how his colleagues have reacted to his return and it's a characteristic response: "Oh they hate it," he says deadpan, pausing to sip the drink Emily offers him through a straw.
He finds children generally adapt more quickly to someone in a wheelchair than adults, who sometimes don't know how to behave. "I think a lot of people are intimidated initially. They don't feel relaxed. With the older generation there's a lot of patting on the head - there still is - that's just the way it goes," he says. "I think the thing is you've not to get too upset, because if that winds you up you'd be wound up all the time. And once they get to know you, people just treat you the same."
He'd only been at this school five months before the accident happened, but had impressed pupils and teachers with his straightforward manner and enthusiasm.
It frustrates him to miss out on the physical rough and tumble with his own children and he misses doing activities with them: "Just the snow - I want to go out and pan the kids with snowballs," he says. "Rebecca's doing badminton and other sports and they've been ski-ing and snow-boarding and that's the kind of thing I would have wanted to take them to do."
But Mr H isn't one for brooding on what might have been. "I've definitely had ups and downs," he acknowledges. "Every day is challenging. Practically it's like a regime and you've got that every day, so you've got to face it, which can sometimes be quite discouraging. But I still think things are going to work out."
His parents were missionaries and Dave spent the first few years of his life in Africa. He's very active in the church and says his faith has given him strength to persevere in difficult times.
"It pulls you out of the gutter sometimes, because regularly you have got to deal with a lot of negative emotions that come with the situation.
"It can be very challenging keeping the right mindset, because at points you just think this is all too much and there are too many problems to overcome. At every turn there is something - you won't go through a day without something to deal with. You've got to have the energy to deal with that and it's finding the strength and energy to do it."
He talks about a friend whose sister recently died of cancer: "You've just got to be thankful you are here. You have a short time here anyway, so you've got to make the best of it. That's my outlook. It does bother me from time to time, but generally I have just got to ignore that and focus on the better things."
Faith and science keep Dave Henderson believing that he will walk again one day.
"I think I will, I still do - I still believe that," he says during a break between classes. "There's just no reason that it shouldn't happen. Everything is progressing, miracles happening all the time, things that people can't explain," says the 36-year-old teacher.
He has friends who are monitoring developments in stem cell research on his behalf and he's encouraged that human trials are under way. "There are breakthroughs coming in the science world. And from that point of view, I am still optimistic that we will see improvements and see things change."
Physio is an important part of his regime and he's also fund-raising to improve his leg bike with pads he can attach to his legs to stimulate the muscles to allow him to exercise them.
"I get physio three times a week to keep everything stretched out and loose, so that if there is a breakthrough or something happens, then I am in good condition."
His own mobility hasn't changed much recently: "From a personal level I have not seen any improvements since the two-year mark; really there wasn't much after that. But it doesn't really discourage me - I am still very optimistic about what's going to happen."
His optimism is infectious.
- Original headline: Daily struggles and victories that make Dave Henderson the comeback kid