Toddlers can be taught to count

The NY Times reports:

For much of the last century, educators and many scientists believed that children could not learn math at all before the age of five, that their brains simply were not ready.

But recent research has turned that assumption on its head — that, and a host of other conventional wisdom about geometry, reading, language and self-control in class. The findings, mostly from a branch of research called cognitive neuroscience, are helping to clarify when young brains are best able to grasp fundamental concepts.

In one recent study, for instance, researchers found that most entering preschoolers could perform rudimentary division, by distributing candies among two or three play animals. In another, scientists found that the brain’s ability to link letter combinations with sounds may not be fully developed until age 11 — much later than many have assumed.

Is this a joke? Doesn't every parent and preschool teacher know this stuff? How is it possible that all the educators could be so wrong about something so obvious?