This year is the first time that I will have the unique opportunity to teach General Chemistry using the Next Generation Science Standards (NGSS), the Standard and Higher level chemistry curricula of the International Baccalaureate Diploma Programme (IB), and Advanced Placement Chemistry (AP). It is rare to find a school that offers all of these curricula to its student population, and even rarer for one teacher to teach them all at the same time.

When I mentioned this situation to friends this summer, including some who are teachers, I was assaulted by a barrage of questions, the most common being, “What’s the difference?” I posed this same question on social media myself, and the responses I received reflected a similar level of unfamiliarity and misunderstanding. This forced me to think deeply about the differences, similarities, and relationships among these three sets of standards. What are their goals? How are the standards different? How are they assessed? Do they work together, or are they separate entities? Which do I prefer?

All of these are great questions and, since I have taught all of these curricula separately, I am in a somewhat unique position to share my first-hand experience and understanding. In this article, I’ll try to shed some light on the topic and answer a few of these questions.

Origins of the courses

The NGSS were developed in part by the National Research Council, the American Association for the Advancement of Science, and Achieve.org. They are a set of “high-quality college and career ready standards” designed for all students from kindergarten through 12th grade, with the stated goal of making science accessible to learners at all levels. Since NGSS is not an “advanced curriculum,” it doesn’t have a direct analog to either AP or IB. However, if you read the source papers, you will find that the language and philosophy of each curricula is remarkably similar, all having been revised or created between 2013 and 2015. Both AP and IB have put out papers detailing how their curriculum works with and extends the NGSS (a topic for another article, perhaps).

Advanced Placement is a set of standards and courses run in the United States by the College Board since 1955. The goals of the AP program are to allow willing and academically prepared students to pursue college-level studies while still in high school. AP writes and administers exams worldwide for 47 different subjects each May. In 2018-19, over 22,600 schools worldwide enrolled 2.8 million students and administered over 5 million AP exams, 161,852 of which were in Chemistry.1

The IB Program, on the other hand, consists of four elements that serve students from the ages of 3-19: the Primary Years Program (PYP), Middle Years Program (MYP), Diploma Program (DP), and Career-related Program (CP). The IB Program is run by the International Baccalaureate Organization (IBO) based in Geneva, Switzerland. IB started with the DP in 1968, serving only high school students using their European developed curriculum, later adding the MYP (1994), PYP (1997), and the CP (2012) to serve students at all levels. Part of this goal is met by offering many of their courses at both Standard Level (SL) and Higher Level (HL). The IB’s goal is to develop challenging programs of international education and rigorous assessment. In 2018-19, the DP enrolled 166,000 students at over 2,900 schools worldwide and administered 630,000 exams, 32,688 of which were in Chemistry.2

Comparing AP and IB curricula

Both AP and IB HL courses are generally considered the equivalent of freshman-level introductory college courses. Depending on exam score, students can receive college credit, lab credit, or even skip freshman courses. IB SL courses are usually not considered college level on their own, but are when completed as part of the full IB diploma. Policies vary wildly between post-secondary institutions, but generally some sort of recognition is given.

AP courses are designed for one year of study and until recently, have reflected an a la carte philosophy. Launched in 2014, the AP Capstone diploma program offers the option for an AP diploma at schools that apply and are accepted by the College Board. To be awarded an AP Capstone diploma, a student must pass four AP courses over four years of high school and also take and pass both the AP Seminar and AP Research classes. These two classes, each requiring one year of study, take students through the process of vetting knowledge and conducting and presenting their own research.

Having never taught either of these courses, it is my feeling that AP Seminar is somewhat similar to the IB Theory of Knowledge course, while AP Research is similar to the IB’s Extended Essay and Internal Exam processes. Obviously, none of these are exactly alike, due to the underlying philosophical differences in approach and focus of AP and IB. However, in my mind, they serve similar roles; the former examines the way knowledge is constructed and the latter explores the research practices of various disciplines.

The situation is a little more complex in the IB diploma program: it has a holistic, cross-curricular, international mindset and is generally offered as a complete curriculum. While individual IB courses can be offered separately to students in most schools, for students to earn an IB certificate for the particular course, it is intended that the entire IB curriculum be completed by candidates in two years, and attention is paid to “international-mindedness” in all subjects.

The IB diploma program offers two different types of classes. All subjects are offered in the SL curriculum, while most courses are also offered in the HL curriculum, which is a more advanced course equivalent to college-level work. SL courses can be one or two years in length, and I’ve seen both implemented depending on whether or not the school has a separate, required pre-IB course. HL courses require two years to complete, and I have seen this done a number of ways, including a two-year HL course, a combination of first-year SL and second-year HL, or a combination of first-year AP and second-year HL. The difference between SL and HL, aside from the time requirement, is that the HL contains additional content and extension material within the course core and has more demanding material than its SL counterpart.

For a candidate to qualify for an IB diploma, they need to satisfy a set of requirements in two parts: the Core and Subjects. The Core consists of a Theory of Knowledge course, an Extended Essay research paper, and the Creativity, Action, Service (CAS) project. Each of these items is a demanding undertaking on its own. The candidate also needs a passing score on six subject exams spread over at least five of the six curricular groups. Each curricular group covers a different discipline — for example, Language and Literature (Group I), Mathematics (Group V), and Experimental Sciences (Group IV). Chemistry is one of several course options for students in Group IV. The candidate must also ensure that at least three of their six subjects are HL, and that they meet the minimum required cumulative scores overall and in their HL subjects. This process is much more stringent and structured than the comparable AP Capstone diploma, both in terms of time required and in the interdisciplinary nature of the courses taken by the student.

The exams

Both AP and IB exams are offered worldwide each May, although IB exams (called External Assessments, or EAs) are offered in November as well. The AP exam represents 100% of final summative assessment. AP exams are scored on a 5-point scale by an external panel of teachers, administrators, and college professors, with a score of 3 generally considered as a passing score. Again, IB is more complex in this area — much more. IB has created a unique system of exams in an effort to assess both the content and the skills covered in their courses. The EA constitutes only 80% of the candidate’s final assessment. (Note: I will focus here on the May exams, since the two test dates seem to cater to different populations, and therefore have different statistics). The EA uses a 7-point scale, with a score of 4 considered a passing score.

The Internal Assessment (IA), meanwhile, is a student-generated research project showcasing their ability to undertake the kinds of research, investigations, and performances inherent in the course. It is usually undertaken as part of the second year of study and fulfills the remaining 20% of the candidate’s final assessment.

AP Chemistry has a new course and exam description (CED) for 2019.3 AP teachers are still picking it apart, but the general consensus is that the new CED increases the focus on six science practices over previous years and reorganizes the course’s content into four “Big Ideas” that connect nine Units. These Units represent the traditional “textbook” progression, which limits organic content, does not include nuclear chemistry (covered in AP Physics 2), and has a strong emphasis on analytical techniques and data analysis. The exam is heavily weighted toward intermolecular forces and acid/base chemistry. I am told this is traditionally the focus of American chemists. I can only guess why this might be — perhaps because the revered American chemist Gilbert Lewis was so integral in both of these areas?

IB Chemistry employed its most recent curriculum for first exams in 2016.4,5 The curriculum is currently nearing the end of its review process, and a new syllabus is expected to debut this summer for exams starting in 2023. Again, the nature of IB makes this a bit more complex than AP. The course consists of 11 required Topics and one Option. Topics are your traditional “textbook” chapters. SL and HL share the required 11 topics, but HL has additional higher level (AHL) content in the form of nine more topics which are extensions of the first 11.

The Option choice gives students some flexibility to tailor the course to their needs and interests. Each student chooses one option from four choices: Materials, Biochemistry, Energy, and Medicinal Chemistry. Most teachers I know either choose the option to teach, or allow the class to vote on one option to be taught. These options represent in-depth explorations of applications of the required chemistry topics, with HL studying additional higher-level option material as well.

Similar to the AP, there is a focus on analytical techniques and data interpretation. Nuclear chemistry is covered (slightly) in HL chemistry and in the Energy option, but is covered in depth in HL Physics. Organic Chemistry makes up a substantial amount of the curriculum in my opinion, being integrated into several topics, having its own topic and AHL material, and forming the backbone of three of the options. Again, I’m told that this is a traditional focus of British chemists, though I can only speculate why.

A difference in laboratory focus

Lab skills are not directly tested through a practical exam in AP chemistry; rather, they are included as scenarios on the free-response portion of the exam. There is a stated requirement that 25% of the course should be devoted to hands-on lab investigations, with some of these being inquiry-style labs. To be approved by the College Board, syllabi must reflect these levels of emphasis.

Probably one of the biggest differences between the two is that IB explicitly tests practical lab skills. This is done in several ways to get an accurate view of each candidate’s practical knowledge. First, teachers submit a form for each candidate, detailing all of the practical work completed by the student for review by the IBO. SL requires 40 hours spent on practical, hands-on work, while HL requires 60 hours. These requirements include 10 hours for the Group IV project and 10 hours for the IA, and represents 25% of the course’s instructional time. The Group IV project is an interdisciplinary activity that all Experimental Sciences (Group IV) students undertake. The goal is that students from different group IV subjects (Biology, Chemistry, Physics, Design Technology, Computer Science and, optionally, Environmental Systems and Societies) work together to analyze a common topic.

Finally, the Internal Assessment is a student-driven research project and is a requirement for each IB subject taken. It is essentially a highly-developed formal laboratory report and is a major undertaking. Requirements for the IA are the same in both SL and HL. The Chemistry IA usually requires candidates to carry out an investigation of their own design. The IA is internally assessed and externally moderated. Teachers score the papers on a common rubric and then submit score recommendations to the IBO for moderation. The teacher’s assessment is validated using submitted feedback and a common rubric. IB then either accepts the scores or moderates them up or down.

Analyzing exam data

The AP Exam conducted in May consists of two parts: a 60-question multiple-choice section and a seven-question free-response section. Each section counts for half of the overall score and the students are allowed 195 minutes to finish. The exam is normalized to previous years through a variety of methods, one of them being 10 unscored questions out of the 60 total questions. These questions are the same year-to-year, and do not count toward the student’s score. AP Chemistry has some of the lower average scores and pass rates worldwide for an AP-level class: 2.80 out of 5 and 54.6% passed in 2019. Only the top 8-12% of students have scored a 5 each year since the 2014 curricular review, with 10.7% reaching that mark this year.6 They are never released to the public in an effort to keep the data they collect relevant. These questions, along with other methods that College Board uses to moderate the exam, serve to keep these numbers remarkably stable from year-to-year.

The IB External Exam is completed in three parts, called “papers,” over two days. Each paper covers a specific part of the course. They consist of a 40-question multiple-choice section covering the core content, a 95-point free-response section covering the core content, and a 45-point free-response section consisting of a data-based question and questions about the optional content. Candidates are allowed 270 minutes total to complete the exam. IB Chemistry SL had one of the lowest Group IV SL pass rates in May 2019 (59%) with an average score of 4.01. Only 5.4% received a score of 7 in May 2019. IB Chemistry HL has a higher pass rate, probably reflecting the kinds of students it attracts. This pattern is reflected in other subjects and groups, with HL scoring better than their SL counterparts. For the May 2019 exam, the pass rate was 72%, with an average score of 4.50. Just 8.5% of candidates received a 7 on their exams.7 Much like the AP exam, the IB exam is extensively analyzed and normalized through various methods. This process has kept scores remarkably consistent over the past four years.

Bottom line

Do students even really know what they want or which program would be the best fit for them? This is a tricky question. In my personal experience, teaching at an international school in Asia, students are very concerned with scores. There is a perception that only the most difficult courses count, and that if the students don’t get a perfect score they will not go to university. This is a widespread cultural perception that is reinforced by family and society. Students and parents will do almost anything to get into these advanced courses, even if an advanced course is not an appropriate choice. Not many schools offer both curricula, but for those that do, the role of the guidance counselor becomes even more important in helping students navigate the tricky decision of which course is best for them.

So, the big question is which is best for your students? It really depends on what they want out of the program. Do they want a deep dive into content and data analysis, but don't have two years to do it? Do they want exposure to organic chemistry, but don’t want to worry about the complexities of mechanisms or applications? Do they want to do labs, but are not necessarily interested in doing their own research? If the answer to these questions is yes, then AP is for them. On the other hand, do they want a broad exposure to chemistry, with explicit connections to their other courses of study? Do they want to dip their toes into the ocean of organic chemistry? Do they want to undertake their own research projects to satisfy their own curiosity? If the answer to these questions is yes, then IB is for them. In the end, Advanced Placement and International Baccalaureate have more similarities than differences — they are both accepted by universities around the world, and both offer a good exposure to advanced chemistry for any high school student.


  1. Total Registration. 2019 AP Exam Score Distributions web page. https://www.totalregistration.net/AP-Exam-Registration-Service/AP-Exam-Score-Distributions.php (accessed Aug 14, 2019).
  2. International Baccalaureate Organization. IB Diploma Programme Provisional Statistical Bulletin, May 2019 Examination Session. https://www.ibo.org/contentassets/bc850970f4e54b87828f83c7976a4db6/dp-statistical-bulletin-may-2019-en.pdf (accessed Aug 14, 2019).
  3. College Board. AP Chemistry Course and Exam Description, Effective Fall 2019. https://apcentral.collegeboard.org/pdf/ap-chemistry-course-and-exam-description.pdf (accessed Aug 14, 2019).
  4. International Baccalaureate Organization. International Baccalaureate Diploma Programme Subject Brief, Sciences: Chemistry — Higher Level. https://www.ibo.org/globalassets/publications/recognition/chemistryhl2016englishw.pdf (accessed Aug 14, 2019).
  5. International Baccalaureate Organization. IB Diploma Programme Chemistry Guide, First Assessment 2016. https://www.ibchem.com/root_pdf/Chemistry_guide_2016.pdf (accessed Aug 14, 2019).
  6. Total Registration. 2019 AP Exam Score Distributions web page. https://www.totalregistration.net/AP-Exam-Registration-Service/AP-Exam-Score-Distributions.php (accessed Aug 14, 2019).
  7. International Baccalaureate Organization. IB Diploma Programme Provisional Statistical Bulletin, May 2019 Examination Session. https://www.ibo.org/contentassets/bc850970f4e54b87828f83c7976a4db6/dp-statistical-bulletin-may-2019-en.pdf (accessed Aug 14, 2019).

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