Your group's science model collapsed during the presentation, and the class laughed. Afterwards, your two teammates are upset and trying to work out what went wrong. You know exactly what went wrong: you were in charge of gluing the base, and you rushed it that morning because you'd left it too late. Your teammates are guessing it was the cardboard, or the weight on top. Nobody's looking at you. You could let them keep guessing. Or you could say the thing that's true: it was the part you were responsible for, and you didn't do it properly.