Grade conversion for AP Chemistry
In order to translate the grade on an AP style exam to a percentage grade that goes into the grade book,
I used the 2008 AP Chemistry Exam AP Score Conversion Chart. The chart is given below:
AP Score Conversion Chart
Composite Score Range
100 – 150
81 – 99
62 – 80
49 – 61
0 – 48
AP Score
5
4
3
2
1
I wanted to translate the grades according to the following conversion:
AP Grade
Percent
Grade
5
4
3
2
90+
80s
70s
60s
Using that conversion table above, I graphed the points from the AP Score Conversion Chart as the x-axis
and the desired percentage grade book grade as the y-axis. I also added three additional points by
taking the midpoints of the AP Scores of 4, 3 and 2 to give a total of seven points. The final chart is
below.
AP
Score
5
4
4
3
3
2
2
Points
from AP
Percentage
Score
of AP
Conversion
Exam
Chart
points
100
66.67%
91
60.67%
81
54.00%
72
48.00%
62
41.33%
56
37.33%
49
32.67%
Percent
grade in
grade
book
90%
85%
80%
75%
70%
65%
60%
Below is the resulting graph.
Grade conversion
100%
Grade in gradebook
95%
90%
85%
80%
75%
70%
65%
60%
30.00%
35.00%
40.00%
45.00%
50.00%
55.00%
60.00%
65.00%
70.00%
AP Conversion Percentage
As you can see, the points are nearly linear with the best fit line having a R² = 0.9941 (the closer it is to
1.0, the closer the points are to being linear). The equation of the best fit line is
Grade in grade book = 0.8626(AP Conversion Percentage) + 33.02.
This is the equation that I use on the Excel spreadsheets that I send out with the tests. This equation
allows students to earn grades more than a 100% (the maximum grade is 117%). I can also set the Excel
spreadsheet to have a minimum grade (and you can determine your own minimum grade).
I want the free-response and the multiple-choice to be equally weighted. I will use multipliers to adjust
the free-response questions to be equally weighted with the multiple-choice.
If the test is too hard and too many of your students are not successful on it, then you can always modify
this grade to meet your needs. However, our goal is to get the students to learn the material so they
can be successful on the exam. That being said, I see nothing wrong with letting them do test
corrections to earn back ½ or ¾ of the points that they missed on the multiple choice.