It aims to boost grass roots rugby in schools and involves a six-week introduction to the sport and a competitive tag rugby festival, while equipment and balls are left with each school afterwards so pupils can continue their passion.
Run over the course of the season, the scheme supports 1,200 teachers in 650 schools and the number of boys and girls who have taken part in the scheme is enough to fill Twickenham stadium's 82,000 seats.
And Greenwood, who won 55 caps for England and scored 31 tries, made sure that on top of the coaching, the youngsters walked away with a treasured souvenir.
"The groundsman Keith wasn't looking as I nicked a few blades of grass and said 'take that and put that in your pockets and show your mates at school, genuine blades of grass from the pitch at Twickenham'," said Greenwood.
"A day like this is about getting on the pitch, having some fun, getting a smile on your face and experiencing what it's like.
"It's a wonderful opportunity for them, there's cheerleaders practising rehearsals, there's sound tests going on there's flame-throwers kicking off.
"In the mean time we're teaching them a little bit about basics.
"I've done a few days around the country in Norwich and up in Leicester to see how the academy coaches from the different clubs are working.
"Some of the kids might end up being Tigers or Saracens in the future but more importantly it's about trying to spread the values of rugby which is a great team and family sport and without sponsors like Aviva numbers would continue to shrink because that's a problem for us.
"We want to flip and change that trend with the World Cup coming here in 2015 and you need big guys supporting it in a tremendous way like Aviva do."
Aviva Sponsorship Manager Nick Gibbs was also on hand at the training session and believes some of the players involved in the scheme this year could be stars of the future.
"The children love the fact that they get a Leicester Tigers or a Harlequins coach coming out to the school," he said.
"They also get to go on a rugby transition day and we hope that by introducing them to local rugby clubs they say 'I really enjoy what's happening here and sign up for a local rugby club'.
"Let's hope that does start to get more children coming through and playing rugby and we do start to see some emerging English talent coming through."
The Aviva Premiership Rugby Schools Programme is designed to increase participation in the sport and unearth young England stars of the future. Find out more at avivapremiershiprugby.com