well according to my kid, hes reading the book named as the \"Animal Horn\" many early hornbooks were made by printing letters onto paper or vellum (animal skin) – both expensive materials at the time. To protect them, the letters were covered with a layer of animal horn like cow horns, https://hornsavvy.com/category/sheep-horn/, goat etc so thin that it was see-through. This horn was fixed to a wooden or leather base, which was known as a hornbook. Sometimes the ‘books’ were made from metal, ivory, or bone like this one, but they still kept the same name. Some were even baked out of gingerbread to tempt children to ‘swallow what they read'