French pupils created a windowfarm in order to reduce air pollution in classrooms.

They found instructions on line but had issues with the watering system, especially from one bottle to the next one ("stage" by "stage").

At first pupils decided to make hole in the the plastic bottle top and put plastic pipe as a drop system:

But this system had limits: water was dropping too fast and wasn't well guided. In addition, the waterplastic bottle needed black tape to protec roost from light.

Pupils improved the system with:

- changing the kind of recycled bottle transformed as pot : from water to milk, no longer transparent and larger;

- using 3D designed bottletop fitting perfectly the plastic bottle, they designed it with the help of an engineer :

Here a combination of both systems: on the right the plastic pipes and on the left the milkbottle with 3D printed system:

Then  pupils had to solved another problem: mud blocked the pipes between bottles, so water couldn't drop from one line to the next one . As the water system is based on gravity, it was a big problem!

They came with an additionnal idea: designing a grid!