Do you tell players what they need to roll TO HIT?

Nope...but most of us have been playing since 1978 or thereabouts, so they all have a pretty good idea. My DM style is more descriptive in focus; therefore the dice are just a means to an end and my guys focus on what I'm saying more than the pip count.

Mine too.

Such secrecy bugs me, as it serves no purpose other than to give me more stuff to keep track of and I'm not so interested.

I just tell the players their opponents' AC, and they tell me if they hit.

I figure anyone locked in combat will have a pretty good idea of how difficult it is to damage their opponent anyway.

Nope. I tell my players nothing of the sort. ;D

I don't tell the players, but after a while you know you need a 12 to hit a kobold - so when a 12 misses, it gets interesting ...

I don't, but if the combat lasts more than a few rounds, they can generally deduce what the target number is. I like to not announce the target number because that way I can apply situational modifiers and such without having to explain everything

As I said, the players that care to know are deducing the AC (et al) from the roll and the result.

IAC, when I describe the scene I'll usually mention what the opponents are wearing, and even if I don't players will ask for that sort of information during a fight. When they do I'll, of course, tell them. The PC's are products of their enviornment and in their environment they would *know* what chain mail, plate, leather, etc look like, so the players are entitled to that information.

However, they aren't entitled to *know* exactly what to roll, IMO. Part of the fun, for all of us, is for them to figure it out....

Player A: "A 14! That should be a hit!"

DM: "The large Orc in the chain mail fends your sword off with its shield and laughs cruelly!"

Player A: "d**n! He's higher level that I thought! Little help over here!"

...the player learns that a 14 won't do it and the Orc is wearing chain, he can start deducing from there...

And speculation about the Orc swirls around the table...

Player B: "I hit him with a 14 last turn, but my PC is higher level than your's."

Player C: "This guy must be the boss. Let's concentrate on him."

Much more fun that "Player A, your PC needs a 15 to hit, now roll for it."

That's a good compromise. I might try that out.

Generally, yeah, I don't tell the players squat. I'd actually like to get over the bad habit of saying "you hit" at all, actually. Seems like it would be better to describe hits (and misses!) through narrative. So: Your sword bounces off his armor, or, you knock his helmet off and put a gash in his forehead.

I also agree that OD&D is a pattern recognition / pattern finding game, but I do not find keeping the the AC of a foe secret takes away from learning other secrets. I'd rather keep the mystery solving aspect in every part of the game by keeping the hidden rules behind the screen (the code, or pattern if you prefer) entirely hidden.

It's certainly a preference and not some way of "doing it wrong". But by my understanding, knowledge of the underlying pattern is the primary reward of the game. So any information given by the DM is a reward. By telling players the actual number of a distributive pattern rather than the "verbalized attempt" - "pattern-based response" telling of the pattern, a DM skips the reason the dice are in the game in my opinion. It also puts the math in front of the players as well as making the DC an absolute known (told by "God") rather than a constant repetition of which they are always unsure of no matter how often it repeats.

No.

I use a slightly modified and streamlined Chainmail weapon vs armour table, so there's no actual 'AC' in my OD&D games. You simply have 'chainmail' or 'leather and shield', and different types and sizes of weapons will be more or less effective against it.

I've tried a couple of different ways, each to good effect: giving the players the table and just letting them roll and tell me if they hit, which speeds up play; giving the players a 'descriptive table', which just lists the weapons and what they've best and worst fighting against, and letting them figure out the exact numbers for themselves.

I never had a problem using either method, really. I'm leaning on sticking with the more hidden method, though.

I don't tell them the exact AC, but I'll give them a general idea whether an enemy is particularly agile, slow or well-armoured if they ask for it. I follow the same philosophy for other risky tasks - a competent adventurer might not know exactly how many feet and inches he's going to jump, but he should be able to look at an (exposed) pit and decide whether it should be a breeze for him, a herculean task, or if it could really go either way.

We're talking about adventurers with CLASS LEVELS, quite possibly SEVERAL of them, in a world where the average "civilian" is a 0 level NPC. They should be competent enough to be able to tell an easy job from a hard one.

On a related note, I let my players throw against the treasure table for their own treasures. It's like playing scratch tickets. I tell them what letter they got, and they throw the dice. It's a thrill.

The same. I do'nt care too much. When they're happy with a good score, it's ok. I'm so lazy.