Did the pigs destroy the children's books from which they learnt to read and write from? How long did they try to educate the other animals on the farm?

In Chapter Two of Animal Farm, the pigs reveal to the other animals that they have taught themselves to read and write. They did this over the course of three months and using an "old spelling book" which once belonged to Mr and Mrs Jones' children. The pigs then threw the book onto the "rubbish heap" - an act symbolic of their rejection of human oppression and their seizure of Animal Farm.
After this, Snowball, one of the pigs, decides to teach some of the other animals how to read and write. According to the text (in Chapter Three), the Revolution takes place in June and Snowball teaches these lessons until the "autumn," by which time almost all of the animals on the farm are literate "in some degree." This suggests that Snowball taught these literacy lessons for around three months in total.