Monoculture is a less well-known problem than pesticides for the general public. Its easier to rail against a problem that feels familiar than to teach a somewhat new idea and then discuss the dangers of it.
Additionally, a lot of people like the products of monoculture and the cheap, on-demand, readily-available food business that it enables. It would take a seismic shift for a lot of people to accept discoloration in their mcdonalds french fries, or tomatoes at walmart that aren't all perfectly spherical pinkish orbs.
My intuition from a tiny bit of experience growing worms with home-composting was that the same amount of money spent toward tending properly biodiverse land (incl. micro organisms, mycoculture etc.) could provide much more effective and healthy food sources, only if the requisite knowledge was there. So I thought the most effective donation could be an open source repository of essentially recipes for a biodiverse plot, searchable by weather/temperature, type of soil, types of seeds/animals available at market, which provides instructions for how to set up year round harvest.
An agroforestry look like this: https://sitiocurupira.files.wordpress.com/2008/11/agroflores...
Take very special attention to the ground on the video I linked above. So the main thing is the soil, the work will basically be always improving it by pilling up organic matter, from regular pruning and your organic waste too, the school must have good source of organic waste, also the city gardens/grass pruning are a good place to look for organic matter you could use on this project.
Also, the more you plant together and at the same time the better. On the video you can see Bananas and Eucalyptus side by side, people think that Eucalyptus doesnt let anything grows near it, etc... but then I saw a lot of things fruiting just a few centimeters from Eucalyptus, because of the regular pruning.
I'll send you an email so we can continue to talk about this.