Children use a lot of different books on one subject. Teachers give them theses, reports, and lists of literature or bibliography. Students get ready for the lessons using different books, magazines, encyclopaedias and reference books. Sometimes students use Internet, especially before tests and examinations. Students can do this without leaving school.
All necessary books are in the school library.
In Russia school libraries are poor, they don't have enough books. The addition of new books to the libraries is made very seldom. It's difficult for a student to write a good essay using only books and other materials from his school library, so he has to go to the central public libraries, because only there he can find necessary information. But he spends a lot of time. Time - is money.