Last year I had same concept, if we can plant a tree it will give them fruits at school playground for long time.
So we planted trees in different schools, orphanage centers through my organization Road to 2030 and and school @schoolforsdg4 (previous name community school), last year event "on facebook"
Though, our school has no land, it is a rented room for kids education from slums. it is possible to plant trees near to school. Kids also can join <3. It is also possible to plant in different schools, orphanage centers and area where slums are available and kids suffer from malnutrition. I have plan to do it this year. and will be happy if @alexvan , you and some more people also join in this concept.