A very nice history of Ed-U-Cards appears on the Road Trip 62 blog but one particular picture over there really caught my eye. Take a gander at the paper baseball diamond that came with the Ed-U-Cards deck:
It looks quite familiar. Despite the Ed-U-Cards branding, it is the exact diamond that was sold with bagged sets of 1951 Red Back cards, which were likely marketed by a third party after Topps sold off their excess. There is no Ed-U-Cards logo but it's the same diamond for sure:
Of course this begs the question-did Topps sell their excess Red Back stock to Ed-U-Cards? Or did each company merely license or use the diamond for their own purposes? Here is the bagged set, fronst and back. You can clearly see the diamond is packaged inside the bag:
This bears further investigation....