The preschool line is just the normal bullshit to challenge people's egos so that they will a) comment on it to look smart and give the post more visibility and b) share it to feel superior to their friends and give the post more visibility.
And I'm getting pretty sick of those "challenges" to people. This one is actually a legitimate puzzle; not a hard one, but it's a puzzle. It's tons better than "99% of Americans can't give a male name that begins with O within 2 minutes," or "Most people cannot find the 9 in this field of 8s within 15 seconds." They're both bullshit, but the average person (I really, really hope I am overexaggerating the term "average") feels like he just accomplished a task of smarts and then wants to show it off.
So while the puzzle is actually a good one, I doubt the preschool claim holds any water. It's just some group trying to get views.