From the past to the present. The book was used as an auxiliary in the classroom because it can make us aware of what teachers teach and students can learn to come in advance that the teacher will teach you tomorrow.
From past to present The book was used as a supplementary knowledge in the classroom. It can make us aware of what teachers are teaching and students can study in advance that tomorrow will be taught by the teacher.
From the past to the present. The book was used as adjunct knowledge in the classroom. Because it can make us know what the teacher is teaching and students can study in advance, that tomorrow I will teach you anything.