09 Mar ESS or Biology? Choosing Your IB Subject at SL or HL
Reviewed 4 October 2026 · Current ESS SL and HL course, first assessment 2026.
Should you take ESS or Biology? Compare your interests, the actual SL or HL course, your school’s options and any subject requirements for your future plans. Neither subject is automatically the easier choice, and enjoyment of a topic does not replace checking what the course involves.
ESS or Biology: what would you study?
Environmental Systems and Societies
IB ESS connects environmental science with societal perspectives. You examine environmental processes alongside questions about resources, sustainability, decisions and values. It is useful to enjoy both interpreting evidence and discussing how people interact with environmental systems.
The revised ESS course, first assessed in 2026, is available at SL and HL. HL includes additional content and lenses involving environmental law, environmental and ecological economics, and environmental ethics. See the official IB ESS course update.
Biology
IB Biology focuses on living systems, from molecular and cellular processes to organisms and ecosystems. It also involves practical investigation, data interpretation and explanation of biological processes. Ecology is an area of overlap with ESS, but the courses are not interchangeable.
For a current overview, read the official Biology subject brief, first assessment 2025. Compare the course offered at your school and the level you are considering.
Compare SL with SL, and HL with HL
Do not choose using an old description that presents ESS only as an SL subject. Check the current content, teaching time, assessment tasks and support available for each option. A comparison of Biology HL with ESS SL answers a different question from comparing the same level.
ESS requires accurate science as well as well-supported explanations of environmental and societal interactions. Biology requires detailed understanding of biological processes as well as applying that understanding to evidence. Both need regular practice and an individual investigation.
Which subject is easier to score well in?
There is no reliable shortcut based on the subject name. Your preparation, interest, relevant skills, teaching and chosen level all matter. A claim that only a particular percentage of ESS students receive a 7 needs a dated official source and appropriate context; it should not be used as a prediction of your result.
Try a current learning task from each course with a teacher. Ask whether you can explain the processes, interpret the data and respond to the question. Use that experience to identify what you enjoy and what you would need to practise.
Check future requirements before choosing ESS or Biology
If you have a possible university course in mind, check its current entry requirements directly, including required subjects and levels. Do not assume ESS substitutes for Biology where a programme specifies Biology. Requirements differ between programmes and can change.
Discuss your complete subject combination with your school’s IB coordinator or adviser. Confirm which options your school offers and how the choice fits your plans before making a final decision.
A practical decision checklist
- Read the current official subject briefs and identify the level you would take.
- Write down which topics and kinds of questions interest you most.
- Look at a current course task with your teacher and discuss the skills involved.
- Check your school’s teaching, timetable and available support.
- Verify any future entry requirements with the relevant institution.
- Choose a realistic plan for the full Diploma workload, rather than relying on a reputation for easy marks.
Explore how an ESS lesson could help
If you are considering ESS, bring a topic or a question to a lesson with Marija Maletz. You can explore how environmental evidence connects to societal perspectives and what a structured ESS explanation looks like. This can help you identify learning needs; final subject choices and entry requirements should be checked with your school and the relevant institution.
If you already take ESS, read the current SL and HL exam guide, or explore the fields of environmental science for an introduction to different kinds of evidence.
Need help applying this to your ESS work?
Explore online IB ESS tutoring for SL and HL with Marija Maletz or request a free 20-minute trial. Bring your level, the question or topic you find difficult, and your availability.
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