For YES the students come up with a product or service, set up a real-world business, and end the year with a real profit - or loss.

The fair was the young entrepreneurs' first chance to test their wares and marketing skills on the public, with shoppers voting for their favourite business and secret judges rating the best stalls.

Panguru Area School had Hokianga Sustainable Fertiliser, a liquid fertiliser manufactured from sea squirts, an invasive marine pest now found locally, which competes with mussels, gradually taking over. Allen Karena said tests showed the fertiliser boosted plant growth by 35 per cent.

Springbank student Seth Evans, who recruited mum Vicky to help man his Horsin' Around stall chose horse shoes to make his sustainable art products because they were normally thrown away, but offered a golden opportunity to recycle, re-use and re-create.

He had originally planned to make owls (and had sold his first one), until his father taught him to weld, the owls then evolving into garden art spheres.

Meanwhile the customers' choice award went to Kakariki Pure (kawakawa-based household cleaner, Springbank School), from Aqua Woods (spa pool boards, Kerikeri High School) and Tree to Be (bee-friendly seed growing packs, Kerikeri High School).

The judges chose Tree to Be as the best stall, from Kakariki Pure and Eco Wave re-usable shopping bag key rings, Whangarei Girls' High School.