“Do you know what a frog is?” Kimi Pu, 9, asks her dad with a grin, pointing at a fork. “Frog?” he repeats, sheepish but smiling. “Frog’ is an animal—this is a fork.” “Fork! Sorry!” he says. “Great ...

Seven years later, children who start learning English in the first grade achieve poorer results in this subject than children whose first English lesson isn’t until the third grade. The researchers ...