As the Head Boy/Girl of your School, write a letter to the Principal, requesting him to update the library with Encyclopedia and other knowledge related books.
ABC Public School
28 April 20XX
Subject: Updating the Library
On behalf of all the students I would like to bring to your kind attention that the library of our school needs to be updated.
Although there are good number of books in the library, it will be of great help to the students if a few encyclopaedias and other informative books are added to it. There are some books which are of old editions. Their new editions in accordance with the new syllabus are available in the market, we will be grateful if you can arrange those too.
I hope you will look into the matter.