laboratory scale for head to see,whom is more clever

In these days I brought home a laboratory scale, because I received a relatively a big order for this scale, I took the scale home and at home my child put a lot of things on the scale to compare the weight. Suddenly the child said: Mom, let’s compare whose head is heavier, right ? in the first,the samples I brought home cannot be used for “heavy weights.” and the second, I told my children: smart or not smart – you can’t see whose head is heavier, but the fact that the scientist wants to help you see something inside the head .. The ravine in each part is raised, it is bigger, the smarter. “But the child looked at me in bewilderment, obviously, he did not understand.