Many children already have their own smartphone by the time they’re in primary school these days. And the devices have sometimes been indispensable for Covid-related distance learning. But they also have serious drawbacks, educators point out. Klaus Zierer, professor of education at the University of Augsburg in Germany, says school authorities should take a close look at schoolchildren’s smartphone use, warning that excessive use could lead to massive learning deficits. He says the latest results of research by the acclaimed New Zealand educator John Hattie show that intensive smartphone use …