But the two tasks I’ve described are a real test for
children, developed in Switzerland.
They are phenomenally accurate at predicting full-scale intelligence scores. On
5 and 6 year-old kids, this simple test is virtually synonymous with a
90-minute intelligence test of their full cognitive capacities; the two tests
have a 99% correlation. It turns out that kindergartners who are really good at
sorting line length and relative weight are the exact same kids who score high
on tests of conceptual reasoning, memory, and attention.