The 17-year-old, who can not be named for legal reasons, kept newspaper stories about Raoul Moat and Norwegian mass murderer Anders Breivik along with a stockpile of weapons in his bedroom including a machete and homemade petrol bombs, the Old Bailey heard.
He is on trial accused of planning a terror attack on his former school in Loughborough, east Midlands, as well as naming his sixth form college, a local mosque, cinema and council offices as potential targets.
Prosecutor Max Hill QC said the defendant used Facebook's private messaging service to discuss his targets with a friend, adding: "There are aspects of these Facebook chats which cannot be explained away as schoolyard banter."
The teenager and two other 17-year-old boys have already pleaded guilty to two charges of possessing petrol bombs and component parts of pipe bombs.
The defendant denies possessing items for the purpose of terrorism, one count of possessing a document likely to be useful for committing or preparing an act of terrorism, and a count of possessing explosives.