Although many educators and school administrators, including those working in the U.S. Department of Education, continue to push schools to invest heavily in computer technology, the evidence of any benefit from such investments remains elusive. The biggest beneficiaries of heavy spending on school technology are technology firms. Students, meanwhile, may actually be harmed by having too much tech in the classroom, particularly when spending on hardware and software leaves less money for hiring and training teachers and improving school facilities.

The latest evidence on the effect of computer use on learning, and some of the strongest to date, comes in a large, international study released today by the Organization for Economic Cooperation and Development. Called “Students, Computers and Learning: Making the Connection,” the study “shows that the reality in our schools lags considerably behind the promise of technology,” writes the OECD’s director of education and skills, Andreas Schleicher. Computers’ “impact on student performance is mixed at best.” He sums up the study’s findings this way:

Students who use computers moderately at school tend to have somewhat better learning outcomes than students who use computers rarely. But students who use computers very frequently at school do a lot worse in most learning outcomes, even after accounting for social background and student demographics.

The results also show no appreciable improvements in student achievement in reading, mathematics or science in the countries that had invested heavily in ICT [information and communication technology] for education. And perhaps the most disappointing finding of the report is that technology is of little help in bridging the skills divide between advantaged and disadvantaged students. Put simply, ensuring that every child attains a baseline of proficiency in reading and mathematics seems to do more to create equal opportunities in a digital world than can be achieved by expanding or subsidising access to high-tech devices and services.

Schleicher also notes that the study found that students who spend more than six hours a day online outside of school “are particularly at risk of reporting that they feel lonely at school” and are more likely to skip school or arrive late.

The evidence presented in the OECD study is striking. Here is a chart that compares, by country, the number of computers in schools with students’ performance in mathematics:

As the number of computers goes up, performance in math deteriorates.

Here is a similar chart comparing students’ reading performance with the amount of time they spend using the internet at school:

Again, as time online rises, reading performance falls.

Here are two more charts comparing the intensity of computer use in schools to reading performance. The one on the left compares reading skill, using both paper and digital texts, with amount of computer use. The one on the right focuses in particular on students’ ability to navigate and evaluate online texts

What these charts indicate, as the OECD report explains, is that “limited use of computers at school may be better than no use at all, but levels of computer use above the OECD average are associated with significantly poorer results,” and “even specific online reading skills do not benefit from high levels of computer use at school.” The research showed a very similar negative correlation between students’ computer use outside of schools and their reading skills.

And here is another chart that compares reading performance with different kinds of school computer use, again revealing that beyond a fairly low level of use, performance declines as use increases:

Finally, here are charts that look more closely at the relationship of mathematics skills and computer use:

Here is the OECD’s gloss on these charts: “Irrespective of the specific tasks involved, students who do not use computers in mathematics lessons perform better in mathematics assessments than students who do use computers in their mathematics lesson.”

Every time a study like this appears, a common reaction, particularly among the promoters of heavy computer use in schools, goes something like this: “the technology isn’t being used well.” But that dodges the real issue. As the OECD research and other studies strongly suggest, the best way to use technology well in schools is to use it less.