While this classroom is the first of its kind in El Salvador, more than a dozen “Bottle Schools” have been built by communities in neighboring Guatemala, coordinated by the Hug It Forward organization. The process, pioneered by the Pura Vida organization, requires discarded plastic bottles to be collected and filled with compacted plastic wrappers, like the ones commonly used for commercial snacks. These bottles become "eco-bricks" which are stacked in between chicken wire on either side and then covered in cement. The bottles serve as insulation rather than structural support but the benefits are far greater.
At around $5,000, "Bottle Schools" cost half of what a traditional classroom costs to build,Here's video from their work in Sepalau, Guatemala.
they encourage communities to work together to clean up litter while teaching environmental awareness, plus they give children pride in their classroom as they are part of the project.