Sixth years will require:

The Standard Book of Spells (Grade 6)
Magical Theroy
Great Wirzarding Events in the 20th Century
Advanced Transfiguration
Encyclopedia of Toadstools
Herbology if Fun (Volume 1)
Magical Drafts and Potions
The Monster Book of Monsters
The Rise and Fall of the Dark Arts
Ancient Runes Made Easy (Ancient Runes only)
Reach for the Stars: A Guide to the Stars and Planets (Astronomy only)
Reading Candles (Divanation only)
Home Life and Social Habits of British Muggles (Muggle Studies only)