Rough is right

If kids still don’t understand the fact that your product is not finished, try using early/rough art in the prototype so that it looks less polished.

Why this technique
Explaining the product isn’t ready yet welcomes kids’ opinions and emphasizes no one’s feelings will be hurt if they don’t like something. But sometimes kids still won’t understand this idea. Using sketchier art may more concretely get across that the product is still being developed.