As the economist James Heckman has demonstrated, successful preschools don't increase the intelligence of toddlers or endow them with new knowledge they take to kindergarten.
This wasn't just for young people, parents brought their toddlers, kids were arm-in-arm and absent was the macho bumping of shoulders and territorial stares common at other hip-hop events.
"The reason why toddlers have tantrums is they don't have verbal or cognitive skills yet, " said Dr. Lisa Shulman, an associate clinical professor of pediatrics at the Albert Einstein College of Medicine in Bronx, New York.