I agree with the poster who said to simply act assured. Becoming flustered, or angry, or embarrassed reinforces to a child that a kilt is "weird", and it will be very hard to wipe out that first impression. I was originally going to mention that you could say something about the fact that women wear pants and shoes, but they are different to mens'- and similarly, a kilt is different to a woman's skirt. However even THAT may be too complicated of logic for a child, and in the minds of some stray into cross dressing area- which of course is not what the kilters of this forum are aiming for.