Yes, the story correctly posits that, given three servings of porridge at the same initial temperature, those portions, being of various size, will indeed cool at different rates. And yes, after an allotted time, the largest might still be too hot; but if the medium bowl is now too cold, the smallest couldn’t possibly be just right, because that would violate the Second Law of Thermodynamics.
And I really don’t think children should be reading stuff like that.
Photo by James W. Blinn. Bowls by Certified International. Oatmeal by Quaker.