I don't think kids are any smarter or stupider now than compared to any other period in history. The fact that they can, for the most part, all read what's on their smartphones is proof of that. In my grandparent's time it was the exception, not the rule, for children to be literate, now most are. If the most basic starting point of education is literacy rate than our current kids are likely already among the smartest in history even if they are relatively ignorant from our own more mature perspective.
It is a tale as old as time for the older generation to see the youngest generation as imbeciles. Younger people haven't had as much time to learn, even if they wanted to, compared to us.
"Children now love luxury, have bad manners, contempt for authority, show disrespect for elders and love chatter in place of exercise. Children are now tyrants, not the servants of their households. They contradict their parents, chatter before company, gobble up dainties at the table, cross their legs, and tyrannize their teachers." -Socrates (400 B.C. Athens)