On the eve of the Rugby League World Cup, the sport is enjoying a renaissance in Tonga. On the field, the nation has attracted a host of NRL stars to turn their backs on Australia and New Zealand and opt instead to represent Tonga while, off it, the sport has been entrusted with revitalising the country's physical education curriculum.

Nehumi Vanisi and Johannsi Pataleone Vi are barely old enough to remember when rugby league was the most popular sport in Tonga. In the early 1990s, the 13-a-side code was king in the Kingdom, helped by the Pacific-focused administration of rugby league in Australia.

Over time, rugby union assumed top spot in Tonga but, a generation later, things have come full circle. As the people of Tonga prepare to cheer on the strongest rugby league side their country has ever fielded in their world cup opener against Scotland in Cairns, the sport is enjoying unprecedented popularity back in the islands.

So much so that it has recently been tasked with delivering the country's physical education curriculum, known as movement and fitness, in primary schools across the nation, led by Nehumi and Johannsi.

As development officers for the NRL in Tonga, they use rugby league as an educational tool to promote healthy lifestyles, wellbeing messages, and physical activity through a six-week program that is now running in every primary school in the country at the invitation of the Ministry of Education. The program is supported by the Australian Government through the Pacific Sports Partnerships.

Nehumi, who began working for the NRL last year, explains: "We developed the lessons in conjunction with the Ministry of Health.

"We used NRL education modules about healthy lifestyles and adapted them to suit Tonga."

The classroom-based lessons cover topics such as the importance of exercise, staying hydrated, healthy food choices and getting enough sleep. Outdoor activities use rugby league-themed games to encourage physical activity and teach the basics of the sport.

"Every time we go to a school, they always welcome us and they're so happy to see us," Nehumi says, proudly. "Back when Johannsi and I were at primary school, there was no physical activity. There was nothing at school. We just used to play rugby with a bottle or whatever.

"Now, we run this program and every school wants us back. The teachers learn something new and they can see the kids are excited, and that it benefits them."

The program is running across 52 schools on the main island of Tongatapu, 20 in the island group of Vava'u (the homeland of Tonga's most iconic rugby league player, Fuifui Moimoi), and 10 schools on each of the outer islands. The schools receive a kit comprising classroom educational resources, balls and cones to continue running activities after the six-week program has ended.

"I think the kids in the outer islands appreciate it more because they don't have as much," observes Nehumi.

"They've heard of rugby but they had never seen a rugby ball until we came to their school.

"Even when we give them four balls, they only use one because they want to save them and use one at a time."

Like many Tongans, Nehumi and Johannsi grew up playing rugby union but have switched to playing rugby league as the sport gathers momentum in Tonga.

"I always wanted to play league, but there wasn't that much here before," explains Johannsi. "I followed it on TV and the internet and I always looked up to Fuifui Moimoi. Now, there are more rugby league competitions than rugby union here, and it's getting bigger and better."

As stars including Jason Taumalolo, Andrew Fifita and Daniel Tupou generate unprecedented interest in Tonga during the Rugby League World Cup, the hope is that appeal of the sport, and the social messages that Nehumi and Johannsi deliver every day on its behalf, will only grow.

This story was produced by ABC International Development as part of the Pacific Sports Partnerships funded by the Australian Department of Foreign Affairs and Trade.