More students are taking ambitious courses. According to a recent Department of Education study, the percentage of high school graduates who signed up for rigorous-sounding classes nearly tripled over the past two decades.

But other studies point to a disconnect: Even though students are getting more credits in more advanced courses, they are not scoring any higher on standardized tests.

The reason, according to a growing body of research, is that the content of these courses is not as high-achieving as their names — the course-title equivalent of grade inflation. Algebra II is sometimes just Algebra I. And College Preparatory Biology can be just Biology.

Lynn T. Mellor, a researcher in Austin, Tex., who has studied the phenomenon in the state, compares it to a food marketer labeling an orange soda as healthier orange juice.