The Importance of Command Terms in the IBDP Sciences
Are you teaching an IBDP Science course? If you are and you are not yet teaching Command Terms as part of your course this is the blog post for you! When I first started teaching IBDP Biology while I was teaching in Venezuela I was in such a rush to get through the curriculum that I didn't spend any time at all on the Command Terms. Luckily, after that first hectic year teaching I reflected on my students exam scores and spent some time thinking about how I could help them improve.
What are Command Terms?
If you're reading this post and wondering what Command Terms are, you are not the only one! These are key words that tell the students how to answer a question on the IBDP Biology exam. According to the latest subject guide (first exam May 2025) they inform students of the "depth of treatment required" (pg. 124) for a specific question. If you are using past paper questions in your quizzes, unit tests and mock exams (as you should) then students will be exposed to command terms throughout their entire IBDP Biology experience.
Why do Command Terms Matter?
One alarming pattern I had noticed was that many of my students would not answer what the question was asking, so their answers didn't match the Markscheme and hence they received very few points, especially on those 7 or 8 point Paper 2 questions. This is also an issue with that tricky Paper 2 question with all the parts... yes Q1 with all the graphs to interpret and analysis/evaluation to conduct. For this reason I started allowing my Year 1 students to use the Command Term glossary during unit tests and quizzes so that they began to familiarize themselves with the process of interpreting the command term in the context of the question. I simply took the Command Term Glossary pages from the IBDP Biology Subject Guide and laminated them, then kept them in the student resource area of my classroom, you can check out how I keep materials organized in my classroom in this blog post.
To help you better understand the importance of this matching between the Markscheme & Command Terms I have taken several past paper questions & markschemes to help illustrate the connection. Feel free to use these examples with your students.
Command Term 1: Discuss from the May 2021 TZ1 SL Exam
The command term discuss is defined as "offer a considered and balanced review that includes a range of arguments, factors or hypotheses. Opinions or conclusions should be presented clearly and supported by appropriate evidence." Notice how the Markscheme includes a variety of factors which affect atmospheric carbon dioxide and how the carbon dioxide concentration then affects global temperatures. The range of factors in the markscheme includes human activity, fossil fuel use, deforestation, loss of polar ice and green house gas emissions.
Command Term 2: Estimate from the May 2021 TZ1 SL Exam
The command term estimate is defined as "Obtain an approximate value." In the Markscheme for this question an acceptable range is included, from -62 mV to -65 mV since this is an estimate. Be aware that all quantitative values should include units and a negative sign if necessary, the absence of either would result in 0 points for this question as the IBO does not award half points.
Command Term 3: Compare from the November 2020 TZ0 SL Exam
The command term compare is defined as "Give an account of the similarities between two (or more) items or situations, referring to both (all) of them throughout." One of the first things that jumps out about this markscheme is that all of the acceptable answers begin with "both", they are only describing similarities between the two lines on the graph. Notice as well that it explicitly says "do not give credit for contrasts", students who describe any differences between the two lines will be wasting their precious time and workspace. Conversely when the command term is "compare and contrast" most markschemes award half the points for the compares/similarities and half for the contrasts/differences.
Assessment Objectives & Command Terms
Not all Command Terms are made equal! You may notice in the subject guide that the command terms are grouped by the three Assessment Objectives which appear on the exams. You can see the description of each objective in the screenshot below, taken from page 19 of the IBPD Biology Subject Guide (first exam May 2016). There are many more command terms for assessment objective 3 than for assessment objectives 1 and 2 and assessment objective three makes up considerably more exam questions than the first two, the new syllabus even outlines this, see the next section below.
For this reason I have decided to begin to include the assessment objective (AO) number in the various Command Term resources I have made for my class so they know to prioritize those for AO3. You can find a Command Term domino review game I made here in my TPT shop as well as other resources to practice outlined in this blog post where I discuss the importance of Command Terms for Mock exams.
May 2016 Command Terms vs. May 2025 Command Terms
Luckily there are very few changes in terms of Command Terms for the new IBDP Biology syllabus, they have kept all of the old terms and added one new one Justify, which is defined as "Give valid reasons or evidence to support an answer or conclusion." For this reason I am updating all of my Command Term resources to include this new one in time for next year's students and should you have already purchased an activity like my Command Term crossword puzzle you will be notified with a free update in your email once it has been updated to include the term justify.
The IBO also added a table which clearly states the percentage of questions from each assessment objective, which you can see below. I found it on page 23 of the IBDP Biology Subject Guide (first exam May 2025). As you can see AO3 is worth the same amount as AO1 & AO2 combined, so incorporate those command terms into your course regularly.
I hope that this post was helpful as you begin to prepare for the IB exams in May and the new syllabus launch next school year.
Thanks for reading teachers, travelers and curious souls of all kinds!
The Roaming Scientist
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