Here’s a simple test to determine the intelligence of a small child:
Pry open a large binder clip. Ask a child to put their finger in the binder clip.
If the child puts their finger in the binder clip, the child is probably dumb.
If the child refuses the request, the child is probably smart.
If the child slides their finger horizontally into the space at the back of the binder clip, the child is probably a genius.
This test would probably work on adults, too, but it’s socially awkward to ask an adult to put their finger into anything, so I would advise against it.