PRESIDENT OBAMA’s domestic agenda, which he announced in his State of the Union address this month, has a lot to like: health care, maternity leave, affordable college. But there was one thing he got wrong. As part of his promise to educate American children for an increasingly competitive world, he vowed to “protect a free and open Internet” and “extend its reach to every classroom and every community.”

More technology in the classroom has long been a policy-making panacea. But mounting evidence shows that showering students, especially those from struggling families, with networked devices will not shrink the class divide in education. If anything, it will widen it.

In the early 2000s, the Duke University economists Jacob Vigdor and Helen Ladd tracked the academic progress of nearly one million disadvantaged middle-school students against the dates they were given networked computers. The researchers assessed the students’ math and reading skills annually for five years, and recorded how they spent their time. The news was not good.

“Students who gain access to a home computer between the 5th and 8th grades tend to witness a persistent decline in reading and math scores,” the economists wrote, adding that license to surf the Internet was also linked to lower grades in younger children.