Breath Test

So...I'd say overall Kate is an honest kid. However, when you ask her if she brushed her teeth, you probably shouldn't take her word for it. Sometimes I'll say, "Kate, did you brush your teeth?" She'll respond, "yes." I'll say, " Kate, did you really brush your teeth?" She'll respond a little more enthusiastically, "Yes!" Sometimes I'll even say one more time, "Kate, are you sure you brushed your teeth?" Again the answer is in the affirmative. But when I follow with, "Let me do a breath test, she'll almost always say, "O.K, O.K, I'll brush."