" Following the 1941 aerial attack on Pearl Harbor, the U.S. Navy Bureau of Aeronautics put out a call to action, aimed not at recruiting adult volunteers or teen enlistees but schoolchildren. Across the country, kids were asked to create 500,000 scale aircraft models to help millions of civilians and soldiers tell friends from enemies during World War II."
“Your country needs scale model planes for the emergency,” read a public call for identification models. “They won’t be used in a display gallery or to show the handiwork of one’s leisure time. They will serve a definite purpose. They will be used for training military personnel in aircraft recognition and range estimation in gunnery practice. These models likewise will be important in the training of civilians in enemy plane detection, an essential element in civilian defense.”
(Recognition Models: Scale World War Miniatures Used to Tell Friends from Foes. by Kurt Kohlstedt)