Students from La Mare de Carteret, Castel and St Mary & St Michael Primary Schools were confirmed as winners.
There were nearly 70 entries from across the Island.
Ellena Loveridge, age 6 of St Mary & St Michael Primary School came out top in the age 6 to 8 category with her idea of recycling the schools old wooden play equipment using a wood shredder to create natural wood chip ground covering to help the environment.
The judges met with the shortlisted entries for the age 9 to 12 category but couldn't choose between the final two and announced them both winners. Marla Naftel's entry for La Mare de Carteret Primary school was a clever plan to replace the school's bottled water fountains and by designing a special water filter system to utilise rainwater for drinking.
Castel Primary School's entry from brother and sister duo, Isabella and Tomos Powis included a detailed presentation and video to create a fully sustainable fruit and veg patch the whole school could get involved in. This included everything from composting fruit peelings from lunch boxes to collecting rainwater for the plants, to selling the organic produce at local farmers markets and investing the profits back into the garden.