I ran across this at an estate sale and thought it was really neat. I can find anything similar on the Internet. I'm not sure if it's of any value but I thought you folks might like to see it and MAYBE have a little bit of info. Sorry pics have shifted a bit. Still getting used to Imgur.
Well seeing as they conviniently included a nice translation, not much can be added.
But I can tell you where it is from. It is from a small village in Takeno Mura in the County of Funai, Kyoto. These are from the junior red cross organization rather than school. They are from Takeno Elementary School.
It is now a modern day elementary school in a very rural area, with a total of 39 students across all grades! Here is their website, and maybe you want to contact them for this find? It would be cool to share around.
Better photo of the letter. Not upside down...