These cute readers are from Scott, Foresman Company, and are part of their diagnostic and developmental reading series. I'm not exactly sure what that means, but I can guess it might have been used for remedial or supplemental purposes. I have many many readers from a variety of book series, but since I'm not an educator, it's hard to figure out exactly which books were used for what purpose. They were published in 1967, and I have one first grade, two second grade, and one third grade reader.
Scott, Foresman was the publisher of the iconic Dick and Jane series of books. However, once Dick and Jane had outgrown their relevance in the American elementary schools, they were replaced by other types of readers, which focused on a variety of learning segments: poems, fantasy, social studies, problem solving, etc. Rather than following one set of characters in the early readers, these books relied on short, interesting and varied chapters, which reflected more about the world the child really lived in.
The new world of readers included stories and chapters about different ethnic and cultural groups, and a much wider range of developmental experiences. I hope you enjoy looking at the cute illustrations from these readers. They are wonderful examples of art from the 60s.... stylized and fun.