The booklet Ben sends away for is for "Dynamic Tension," a system of physical exercises made popular by bodybuilder Charles Atlas in the 1920s.
When John Boy heads over to see Miss Hunter with the buttons & preserves, Olivia takes off his glasses before he heads to the barn to get on Blue. She doesn't stick them in his pocket. At the boarding house, Miss Hunter asks him to read aloud his essay. He reads without his glasses. Usually he reads with his glasses.