Within the last week, classes have begun at most four-year universities and community college around the country. But for a significant number of high school graduates, the first semester of college will find them taking remedial classes to learn skills, mostly math and English, that they should have learned in high school.

This repetition of high school-level work is estimated to cost colleges, students and taxpayers as much as $7 billion a year. The fact that this is such a widespread problem should be better understood by the public.

Last week, ACT, one of the two college entrance test companies, issued its annual report, which revealed that only about 30 percent of high school students taking the ACT exam have the skills in reading, math, English or science to do college-level work.

An unavoidable conclusion is that too many high school students are earning diplomas without having the basic skills a high school graduate should possess.

With more states adopting proficiency exams tied to high school graduation, the numbers of students taking remedial classes at college should decline over time. But for too long, the costs of dealing with ill-prepared high school graduates have been pushed onto four-year universities and community colleges.

Creating, staffing and funding remedial courses is a diversion of resources for community college administrators and can be discouraging for the students required to repeat courses they took in high school.

According to the Community College Research Center, about 60 percent of community college students enroll in at least one remedial course. Some of the students in this figure could be “non-traditional,” older students who might have forgotten high school math and need a refresher.

The open enrollment policy of most community colleges means more students will need remedial work, but that policy is also a strength of community colleges, creating opportunities for higher education that decades ago did not exist.

Still, a high school diploma should mean something. And the high percentage of high school graduates required to take remedial courses suggests weak standards at too many high schools.

Proficiency exams being introduced by many states should address the problem. Another helpful step would be to have community colleges make public each fall a report showing which high schools graduated the students taking remedial courses because of low placement scores.

Different states are taking different approaches to reduce the impact of remedial classes. Some states, including Florida, are working to push responsibility for high school graduates ill-prepared for college work back to the high schools, where it belongs.

There is no “one size” fits all answer. Older students entering college after years of working might still need remedial courses.

There will always be a need to help some students entering either universities or community colleges, but the public should be more aware of the scope of this problem, its costs, and possible solutions, which could help students succeed while saving community colleges, students and taxpayers money.