Reflections of an AP Chemistry Exam Reader

Utah landscape with text "AP READING"

I was lucky enough to be selected to read the Advanced Placement Chemistry Exam in Salt Lake City, Utah this past June for the second time. Let me share some of the tips I learned.

Reading the Advanced Placement Chemistry Exam was an extremely valuable experience. Being exposed to how students around the nation answer these challenging chemistry questions was probably the best professional development I have ever received. Generally, chemistry readers are trained and assigned to one question of the seven free response questions asked on that year’s exam. Sometimes, readers will be moved and retrained on a different question later on in the week depending on how long the question takes to grade. By the end of the week all readers have seen thousands of responses to only 1-2 free response questions; from short, sweet and to the point logical answers to confusing, superfluous, and imaginative incorrect answers. After reading thousands of answers over the course of two AP Chemistry readings, I would like to share some pointers that AP Chemistry teachers should consider sharing with their students during the AP chemistry course in order to best prepare them to be successful on the exam.

First, familiarize your students with the format of the AP exam. Based on my experience, it is evident that many students go into the exam blind to what is going to be asked of them. It is important they understand the format of the exam to allow for proper expectations and to plan their time most effectively. I recently posted about the exam format, but here are a few pointers:

  • The AP Chemistry Exam Section I consists of 60 multiple choice questions in 90 minutes.
  • The questions are bound in a book with a reference table.
  • The AP Chemistry Exam Section II consists of three long questions, each requiring an average of 23 minutes and awarding the students up to ten points each, as well as four short questions requiring an average of nine minutes and awarding up to four points each.
  • Each free response question is written on one to two pages with no space for work. After the entire question, multiple pages of paper are provided in the bound book for the responses.

It is important for the students to see this formatting before the exam so they know how they want to organize their work. I recommend giving the students a practice exam so they have experience with this set up. You may choose to give an old exam; but be aware the students have access to the answers online. If you completed the AP audit, you have access to multiple practice exams. These practice exams are secure; meaning that they should not be posted on any websites or available for students at home. Therefore, it is important for AP chemistry teachers to be sure to keep the tests in class only so other teachers can use it as an authentic assessment.  My students took all of the practice exams at some point in the school year and when I asked what the most valuable tool was for reviewing, the majority of students mentioned these practice exams. The students were able to practice time management and actually see the format of the exam prior to exam day.

Students need to learn to organize their free-response answers properly. Readers must read all the pages of work surrounding and following the question they are grading. So if the student writes some answers next to the questions and others on the extra paper, we grade it all.  But there are some serious problems that can arise when students are unfamiliar with the exam format and what is expected of them.

As mentioned previously, the free response questions are written with very little room for students to work their answers out in the space provided below the question. The exam is not designed for students to complete their work on the exam booklet near the question (unless there is an answer box such as for Lewis diagrams). They are supposed to show their work and answers on the provided spaces after each question within the answer booklet. I understand that it can be difficult for students to continuously turn the pages back and forth in order to see the question and then write their answers. But it is definitely better than trying to write in the tiny spaces between questions. Too often students write too small and it is nearly impossible to read the response. The students who write that small in pencil also have the problem of writing too softly making the answers too light to read. If it is impossible to read, readers usually call upon their table leader to help them read the student’s response. However, if the answer is illegible it will not receive points. Rather than writing tiny, students should know to write their work and answers in the appropriate areas of the exam, after the question. For long written responses the amount of room between the sub-questions is entirely insufficient. And for long mathematical questions students trying to squeeze their work in to that small space will suffer lost points if the reader can’t find key numbers and logical work that is labeled and clear. If a student wants to ensure they will receive their maximum points they should write all the answers in one location, and only write their answers once! So many students wrote their correct answers next to the question and then realized they had extra paper and decided to transfer their work over. The problem is, a large fraction of those students transposed answers wrong or gave entirely new answers. So now many students have two sets of different answers. Generally speaking, the readers are told to take the second answer only. This year I have organized all my major assessments to look like the AP exam, this way my students are trained on the best way to organize their answers all year long.

All mathematical questions require work, even if the question doesn’t explicitly say so. Readers cannot award points for correct answers if there isn’t at least a set up given. This year I read question 1 of the 2018 exam including a two-point question requiring students to convert molarity and volume to mass. The students were awarded one point for finding moles and a second for finding the mass. The correct answer can be easily found all in their calculator but if the student only recorded 7.91g they received 0/2 points. They had to show work (0.10000L x 0.500M = .0500mol and 0.0500mol x 158.1g/mol = 7.91g  NOTE: significant figures were not graded on this question). Students received one point for the initial mole calculation and the second point for the mass calculation.

If there is a place for students to draw particle diagrams, Lewis structures, graphs, or any other drawing, and the student makes a mistake within that area they are more than welcome to cross it out and redraw it on the extra paper. Crossed out answers are never read.

Students may not understand the question prompts. It is important for students to know what key prompts mean such as the prompts outlined the table below. Many teachers may find teaching this prompt vocabulary is not within the scope of AP Chemistry; that the students should already know what these terms mean. But if you want your students to perform at their best ability, it is important to outline the expectations of each prompt so the students know exactly what to provide in their answer. The following chart has a small list of prompts that have been seen in the more recent exam questions. The “meaning” next to each prompt is how the prompt is explained in my classes.




Justify your answer

Show all math work and explain how one knows the answer is correct using new information not presented in the question.


State evidence

Use information from the question (data chart, graph, etc.) to prove a statement and provide reasoning including new connections not already made in the question

Notice that “state evidence” is different from “justify” in most cases because the question is specifically asking the students to refer to given information.


Show all work with the appropriate equation used, significant figures, and units for the answer.



Make clear by describing in more detail with new relevant facts.



Draw or model the description provided.

A particle diagram and specific directions often accompany this on how to draw the particles as well as many particles to draw. Students must follow the rules to obtain credit.


Select the correct answer.

Generally speaking, a short answer will suffice. No justification needed.


The value has a range of answers but must be with in an acceptable range and with proper significant figures.

If the glassware used reads to the hundredths place the estimate must have the hundredths place value.

In terms of

Use the following words in the explanation along with new relevant details that connect to the terms.

Have students underline the terms required and after answering the question, check to be sure they used the terms or a synonym to the term.

According to the graph

Find evidence in the graph that explains the phenomenon and explain your reasoning.



For example, I graded question 1(e)(ii) from the 2018 exam requiring students to convert a previous answer to kJ/molrxn and “include the appropriate algebraic sign with your answer.” An alarming number of students obtained the correct value but never provided the correct negative sign. And because the question required the algebraic sign, readers could not accept the term “released.” Therefore, any answer that did not also include the negative sign was not awarded full points. Additionally, in question 1d of the 2018 exam, students were asked “According to the graph, what is the temperature change of the reaction mixture?” Unfortunately, hundreds of students answered this question by stating, “the curve of the graph increases and then plateaus”, never providing a numerical answer.

The exam is not wrong. This is something some students battle with. Question 1(f) of the 2018 exam asked: “The magnitude of the enthalpy change calculated from the results of the second experiment is the same as the result calculated in part (e)(i). Explain this result.” Many students refuted this statement, saying the student must have done the second trial incorrectly, awarding the students no points. The students should have explained the comparison by mentioning that both the magnitude of heat increased and the amount of moles increased by the same factor and when divided to obtain kJ/mol the factors canceled.   However, if a different question asks students to “agree or disagree” with a statement, this is the time the statement could be incorrect. For example, the 2018 exam question 2(c) question asked, “The student hypothesizes that increasing the temperature will increase the amount of N2O3(g) in the equilibrium mixture. Indicate whether you agree or disagree with the hypothesis. Justify your answer.” I have heard from question 2 readers this year that many students answered the question vaguely and never actually wrote if they agreed or disagreed, thus earning no points. Make sure your students have practice with these types of questions.

I hope you found the reflection and pointers beneficial and you can incorporate some of the ideas. Personally, having read the exam two years in a row, I have walked away with so many new ideas and insights that I have tried to share. I recommend looking into becoming a reader (details on! Most teachers I have met at the reading say that reading the AP Chemistry Exam is the best professional development they have ever had. Additionally, fellow AP Chemistry readers and I will be holding a mock reading at the ChemEd Conference, this July. If you are interested in attending, follow the link for details.