WASHINGTON » It’s long been known that schoolchildren in the U.S. haven’t measured well educationally when compared with international peers. Now, results of a new test show adults don’t, either.

In math, reading and problem-solving using technology — all skills considered critical for global competitiveness and economic strength — American adults scored below the international average on a global test, according to results released Tuesday.

Adults in Japan, Canada, Australia, Finland and multiple other countries scored significantly higher than the United States in all three areas on the test. Beyond basic reading and math, respondents were tested on activities such as calculating mileage reimbursement, sorting email and comparing food expiration dates on grocery store tags.

Not only did Americans score poorly compared with many international competitors, the findings reinforced just how large the gap is between the nation’s high- and low-skilled workers and how hard it is to move ahead when your parents haven’t.

In both reading and math, for example, those with college-educated parents did better than those whose parents did not complete high school.

The study, called the Program for the International Assessment of Adult Competencies, found that it was easier on average to overcome this and other barriers to literacy overseas than in the United States.

Researchers tested about 157,000 people ages 16 to 65 in more than 20 countries and subnational regions. The study was developed and released by the Organization for Economic Cooperation and Development, which is made up of mostly industrialized member countries. The Education Department’s Center for Education Statistics participated.

The findings were equally grim for many European countries — Italy and Spain, among the hardest hit by the recession and debt crisis, ranked at the bottom across generations. Unemployment is well over 25 percent in Spain and over 12 percent in Italy. Spain has drastically cut education spending, drawing student street protests.

But in the northern European countries that have fared better, the picture was brighter — and the study credits continuing education. In Finland, Denmark and the Netherlands, more than 60 percent of adults took part is either job training or continuing education. In Italy, by contrast, the rate was half that.

Education Secretary Arne Duncan said in a statement the nation needs to find ways to reach more adults to upgrade their skills. Otherwise, he said, "no matter how hard they work, these adults will be stuck, unable to support their families and contribute fully to our country."