Teachers use formulas, scales to adjust AP course grades

Grading midterms, teachers must not only work through piles of blue books and scantrons, but also determine how to adjust students’ raw scores. Some departments use scales, some use formulas, some use point addition, but across the board teachers want adjustments to benefit students and create what they consider an appropriate average score.

Bo Lee ’13 said his score on the AP Physics B semester exam jumped from a 68 percent raw score to a solid B.

“It’s great. I thought I failed but it really turned out to be okay,” Lee said.

Physics B finals were adjusted using a formula.

“As a science teacher and someone who is mathematically inclined, I am more comfortable with a formula,”  physics teacher Jesse Reiner said.

When they intentionally give hard tests, teachers expect a greater number of students to achieve lower scores.The goal is to find a way to bring the range of scores closer together, Reiner said. By adjusting grades teachers try to compensate for the distribution of grades that results from a high level of difficulty.

“We want to give really challenging exams,” Reiner said.

As a result, the AP Physics B team needs a way to adjust that will benefit lower scoring students most. Rather than use a scale which feels arbitrary to Reiner, the teacher team uses what he called a geeky formula that involves taking the square root of the raw score, multiplying it by ten and then adding three percent to compensate for new questions used this year that seemed particularly difficult.

Other science courses such as AP Biology use a scale that follows the guidelines of the AP board’s scoring system, though the scale is less generous, Upper School Science Department Head Larry Axelrod said.

AP Chemistry has a set scale that does not change year to year, and Honors Chemistry does not scale any examinations unlike other classes which adjust grades slightly based on students’ performance on a given exam.

“We want to make sure each teacher has around the same average,” said chemistry teacher Krista McClain of the regular chemistry course in which each teacher makes their own tests and determines their own scale.

AP Calculus AB uses a scale close to the AP system for which scoring five sevenths of points correlates with a five on the AP exam and an A- on the midterm and final, math teacher Catherine Campbell said.

Scaling doesn’t vary much year to year. Math instructors teaching the same course make a sliding scale based on the scores in all sections so that the average score is between an 85 and 90 percent.

When multiple choice is given for semester exams, both the History and English departments use item analysis provided by the scantron machine, which shows what percentage of students got each question right. They add a consistant number of points to each raw score.

“We only get to use the scantron machine once a year, so it makes us a little giddy,” Upper School English Department Head Larry Weber said.

Weber said teachers on the AP Literature team pull a couple of random blue books from the stacks and grade them together.

“We were looking for the difference between a B+ and an A,” Weber said.

When they are making the question and during these sample gradings, English teachers establish a rubric specific to that assignment.

“We want to be really mindful and fair in how we weight our assignments,” Weber said.

Weber noted teachers do have some “room to play,” to either reward an upward progression or help out a normally strong student who couldn’t get grounded in the analytical section of the exam.

On history midterms some points added to the raw score to cover for scantron mistakes, unclear questions, and “a couple of extra points of pure generosity” are added, Upper School History Department head Katherine Homes-Chuba said.

Teachers sit together and talk about their expectations for student’s written work. Holmes-Chuba said they are sometimes more lenient when grading a semester exam  than they would be on a term paper or even a regular test since it demands comprehension of so much information. She does, however, think studying for finals is valuable.

“Students get to step back and look at the whole semester and realize that it’s not bits and pieces,” Holmes-Chuba said.

Latin teacher Paul Chenier said midterm grading policy varies greatly between classes in the Foreign Language Department.

“Each language is sort of its own world,” Chenier said.

For AP Latin, Chenier does not adjust exam scores. Instead, he tries to balance the difficulty of multiple choice and free response questions.

“I include questions that act as the curve,” Chenier said. “I balance my exams that way.”

He said he expects students’ miderm scores to be within one letter grade of their normal achievement.

“For the kids it’s a chance to prep for the actual AP exam. For me it’s a chance to adjust my teaching strategies,” Chenier said.

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