Not the answers I am looking for

Does anyone else experience this?

We're looking at a word problem, for instance one that goes like this: "Timmy has 18 marbles. He gives 5 to Fred and 6 to Becky. How many marbles does Timmy have left?"

I walk around the room to see how the kids are doing. I notice one of them has subtracted 6-5. I ask him, "Please tell me why you have subtracted 6 minus 5 here."

He replies, "So that I could get the right answer."

Undeterred (I've heard this one before, after all), I persist: "But how do you know you were supposed to subtract these numbers?"

He responds, "Because it says, 'Timmy has 18 marbles. He gives 5 to Fred and 6 to Becky. How many marbles does Timmy have left?'"

Ironically, I will get these exact same answers from a child in the next class who has ADDED all three numbers.

No matter how many times I try to tell the kids that reciting the word problem in its entirety does NOT explain how they got their answer -- kids still try it.

Unfortunately, sarcasm is often lost of them, so me trying to turn this around on them usually fails miserably.

"Mister Teacher, why haven't we gone to the computer lab lately?"

"Because we had fried chicken for lunch today."

"Mister Teacher, why can't we go outside for recess today?"

"Because the Pledge says, 'I pledge allegiance to the flag of the United States of America...'"