Fourth class children encouraged to join library By Alison O'Reilly Children aged 9 to 10 are being encouraged to join their local library. It's part of the 'Join Up, Join In' which will see every fourth class child in Dublin receive a library bag, a book, a brochure and a membership form. Dublin City Council's library team chose the year group as that's when children begin to decide what they enjoy reading. Dublin North-West TD and former Lord Mayor Paul McAuliffe says it is a step in the right direction.