A Budding Pinnochio?

So today my son and I were sitting around talking about his class, and he told me, "Mommy, anyway, you're not going to like this and please don't be mad at me, but today I knocked down a very impressive castle and told the teacher another kid did it."

I asked if the other kid had gotten in trouble. "Yes," the kiddo said, "he got a time-out."

Hmm. I thought about this for a few minutes before climbing on my soapbox and saying things like "personal responsibility" and "honesty" and the like. Well, actually I used somewhat simpler language, and asked the kiddo how he would feel if someone did something naughty and told the teacher the kiddo had done it and the kiddo had gotten a time-out. "Not good," he replied. "Like kind of medium mad and medium sad."

I told him we need to tell the teacher the truth (and tell the truth at all times). "Well, maybe you could talk to the teacher for me," he suggested, "because I'll probably forget about it by the next time I go to my class."

I suggested that he write a note, with Mommy telling him the letters, to the teacher to tell her what had happened, to apologize, and to assure her that he will tell the truth from now on. We haven't written the note yet, and the kiddo says he wants to tell his dad about it himself.

But I'm wondering what some of you have done or would do in a similar situation. Anyone?