No parent ever forgets the moment they are told their child has died in a car crash, but perhaps Brent and Christine Laurenson relive that horror more than most.
Since a few months after the July 2009 crash that killed their son Nathan and his mate Udo Fourie, both 18, in Grays Rd, near Plimmerton, the Laurensons have been fine-tuning a DVD about the pain it caused them, called The Ripple Effect.
The former Porirua couple, who now live in Blenheim, presented the DVD and spoke to pupils at Mana and Aotea colleges earlier this year.
They plan to do the same at 23 schools in Marlborough, Southland and the Nelson-Tasman region before August, in the hope it will change young people's attitudes towards driving.
"It's very difficult to do; it emotionally drains you," Mr Laurenson said.
"It's very tough, but I keep saying to myself that we're doing this for a reason ... We're doing this to try and prevent the same thing happening to other people."
Nathan and Udo were in a car driven by James Cupit, then 22, which was speeding along a rural road with narrow, winding bends, in the rain. Cupit lost control, crossed the centre line and fishtailed into an oncoming car.
The Ripple Effect talks about who Nathan was as a person and features interviews with his family and girlfriend about what it was like to lose him.
Seeing some of the "real big boys" at Mana College trying their hardest not to shed a tear while watching the DVD was exactly the reaction Mr Laurenson was looking for, he said.
"You know that you're hitting their hearts, and that was the whole idea, to hit people in the heart rather than throw facts, figures and gore at them."
Road safety charity Brake is running the Road Safety Week event with the help of emergency services, other charities and the New Zealand Transport Agency.
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