Once upon a time there was a class that guaranteed a golden A- for an easy B+ understanding of the material.

Many students in Baker Professor of Economics Martin J. Feldstein's massive Social Analysis 10 class-better known as Ec10-believe this class to be their golden ticket.

But their faith is predicated on a widespread misunderstanding of the impact of the unit test program-a somewhat complicated part of the course's unique grading procedure.

The program has been in place since before Feldstein took over the course in 1984, and has undergone few changes over that period.

But despite Feldstein and his teaching fellows' best efforts, confusion and frustration about the system prevails among many of the class's over 1000 students.

The tests- optional pass-fail quizzes spaced throughout the semester-are designed to be easily passed.

There are no time-limits, opportunities to retake each test, and infinitely sympathetic graders.

"The thing I've figured out about the unit test," said Adrian Foo '04, "is that you can go in and get most of it wrong and still pass if you sit down and have your grader explain where you went wrong."

According to numerous teaching fellows, the tests also give students a way to benchmark their academic progress and clarify their understanding of core concepts with former Ec10 students who go over students' answers with them immediately after the test.

"It encourages students to keep up with the material," said teaching fellow Thomas K. Cheng. "Otherwise there's a huge incentive to fall behind until the exam."

How does a unit test affect my grade?

"For each unit for which you pass one test, your grade will be raised by 1 point on the 100-point scale that section leaders use to determine letter grades," the course's syllabus says.

But despite this apparently simple explanation, few students say they understand precisely how the program affects their grade-a confusion that centers around the "100-point scale."

Many students think a 100 point scale denotes the simple grading mechanism they remember from high school where an 88% would yield a B+.

But in Ec-10, the 100-point scale is an expression of each student's ranking in the class-so a student with a B+ could be in the 50th percentile.

Because of the scale, the five percentage points that can be gained from the unit tests have a dramatically lower impact on students who get average grades in the class than on those with either very low or very high grades.

Each student is ranked and given a percentile in the class based on problem sets, exams and section participation according to teaching fellow David Blackburn.

The curve based on the ranking system places the greatest number of students in the middle letter grade groupings, with fewer students falling to the far ends of the spectrum.

Each unit test a student passes raises their grade by one 'percentile,' and the new percentile determines the final grade based on the original curve.

As the syllabus states, "unit tests act like an insurance policy. They certainly don't guarantee that your letter grade will be higher, but if your pre-unit test scores put you very close to the cut-off between two letter grades, passing all of the unit tests will insure that you get the higher grade."

The tests thus disproportionately impact students on the extremes of the class.

Teaching fellow Matthew Choate explains that because so few students get lower than a B- anyway, if everyone in the class passed all the unit tests, virtually no one would get lower than a B-.

But that also means a disproportionate percentage of students at the high end of the scale will benefit from the unit tests. If 15 percent of students would receive an A- without unit tests, a third of them will get bumped up to an A if they pass all five unit tests.

Because there is no "13" in Harvard's 15 point grading system, students who cannot move from a B+ to an A- end up with a 12 rather than a 14.

Justice for All?

Feldstein defends the unit test system that some say is arbitrary, because he says that students benefit from the tests in the long run no matter what their direct influence is on their grade.

"It helps students to see their weaknesses and encourages them to keep up," he says. That's a bigger effect than the small bump in the grade."

Most students openly acknowledge that they don't understand the system, though they are grateful for the checkup and any opportunity to raise their grade.

"It keeps me accountable in the class, and of course I'll take any bonus points," said Steven Kim '03. "Most people take them because they think they'll help their grade."

And as long as everyone is graded by the same system, most students believe the unit tests' impact is fair to all.

But some students are frustrated at having to take the unit tests just to make sure they get the extra points, when they feel like they are already keeping up with the material, and others feel like the unit tests are actually counterproductive.

"The tests don't adequately reflect the material as it would be on a midyear or final exam," said David E. Johnson '04. "They give students a false sense of security."