When designing dungeons for a dungeon-crawl session, consider making one of those rooms an “information” station.
When doing a rough calculation, one in ten rooms in a given dungeon should have this purpose.
(It’s customary to put monsters in about half the rooms, traps or hazards in another quarter and leaving the remaining fourth empty for expansion or thematic purposes).
Consider the tasks that your players are required to perform to achieve the session’s goals. What information do they need to accomplish those tasks? Next, find a way to port those answers into the dungeon.
Now, it is true: any room in your dungeon could serve as an information station. Some experienced GMs prefer to play it by ear, feeding information to the player characters as they explore, doing so when the time feels right rather than waiting for them to reach a certain point in the exploration.
The key thing for novice GMs, though, is to establish it before the game begins. Why? Firstly, dedicating an otherwise empty chamber to this purpose carries a certain amount of weight with the players. It’s a signal, a cue, that the information is important. It is the room’s singular distinction. It may seem heavy-handed, but what is obvious to the GM is not always seen as so to the players. This makes sure they stop, listen and process it.
Secondly, it rewards exploration, a key tenet in this style of game. It makes the room worth getting to and looking over even if there is no treasure or combat monsters within.
Once making the room the “information station,” what form should it take so the player characters can interact with it in a meaningful way for the sake of the adventure?
— Information is archived. It comes in the form of an authoritative book, scroll or inscription. If the PCs require access to an area, it can be in the form of a blueprint. If the PCs need to know how to combat a particular monster, a tome offers suggestions on the creature’s Achilles’ Heel. If the PCs’ actions must be done in conjunction with someone or something else — say it must be timed to coincide with another event — the information can be embedded within a crystal ball or other magical object, say a tapestry with arcane effects.
— Information is bound to a secret-keeper. In other words, an NPC has gained the needed information for themselves. Getting them to share it with the characters requires some form of solicitation or coercion. Perhaps the information is trapped within the NPC by a form of magic, and finding a method to release it is required.
— Information is locked away. In this case, the adventurers usually are required to find the “key” that unlocks or transcribes the information. The key could be magical, or it could be mundane, such as a puzzle or code. Experience has shown that players find “cracking the code” to be a fun experience, provided all the materials needed are at hand and the abilities on the character sheets are accounted for as much as a player’s knack for puzzling things out. Plus, gaining the answer is usually just the first step in a quick succession of related encounters: A leads to B leads to C.