Too many unprepared students are taking algebra in eighth grade, causing them to fall far behind and possibly hurt the progress of classmates who are ready for harder math, warns a national report.

While eighth-graders are doing better on national math tests, those in advanced classes are faring worse, according to the study being released today by the Brookings Institution.

“;We have kids who are misplaced in their math classes,”; said Tom Loveless, the study's author. “;They don't know very much math at all and yet they're taking courses in advanced math.”;

Algebra is considered a “;gateway”; course for higher learning. Students who take it that year are on track for calculus as seniors. Enrollment in algebra doubled from 1990 to 2007, when nearly one-third of all eighth-graders were taking it.

But the study says as many as 120,000 middle-schoolers are struggling in algebra classes across the country. Eighth-grade math results on the National Assessment of Educational Progress, or NAEP, have dropped for students who noted they were taking algebra even as overall math scores have improved.

It said that the average math scores of “;misplaced”; eighth-graders fell well below the average for fourth-graders. The report noted worries that instructors might water down algebra lessons to help low-achieving students, which could result in lower-quality instruction for well-prepared children, the study said.

Participation in algebra “;is a good thing until you over-enroll students,”; said Robert Hillier, NAEP's coordinator for Hawaii's Education Department.

He said that in Hawaii, average math scores rise to 270 from 260, out of a possible 500, when 1 percent to 10 percent of students take algebra, and reach 275 when enrollment grows to 11 percent to 25 percent. But if too many students take those courses, say 90 percent, “;then the scores recede,”; Hillier said.

Isle schools generally have a “;diagnostic test”; in seventh grade to check whether a student is fit for a pre-algebra course, said Dewey Gottlieb, a math educational specialist with the state Education Department.

Since 1990, Hawaii's public school eighth-graders - despite steady gains in the math portion of the NAEP - have been trailing their mainland counterparts.

Isle students ranked 47th among the 50 states and the District of Columbia in last year's test. They averaged 269 points, nearly 30 points behind students in Massachusetts, who led the math ranking. The national average was 281 points.

Hawaii reported having 28 percent of its students in advanced math classes, compared with the national average of 38 percent.

But a state's overall math score doesn't necessarily increase as more students take algebra, the study found.

For example, there were more eighth-graders taking higher-level math in New Mexico, Alabama and District of Columbia than in Hawaii, yet their average scores were lower than those posted by isle students.