Haha, children fail.
When asked to perform a series of motions in order to get a treat out of a box, the human child will copy the adult’s motions exactly. The ape copies the motions as well, until the box is replaced with a translucent version. Once it is, the ape realizes that half of the motions are pointless and takes a shortcut to get the treat; children, on the other hand, continue to do the meaningless motions that they were taught.
I kind of see that as the wrong thing to do, but apparently the filmmakers concluded that the children were “better” at learning.