Interdisciplinary IB units work when two subjects contribute distinct knowledge, methods, and perspectives to a problem that neither can adequately address alone. In the Diploma Programme, this means more than teaching related topics simultaneously. Students must use both disciplines and integrate them into a stronger explanation, judgment, or solution.
This guide explains how DP teachers can select a worthwhile inquiry, protect disciplinary depth, design synthesis, and assess learning. It also distinguishes DP expectations from the formal interdisciplinary-unit requirement in the Middle Years Programme.
What counts as an interdisciplinary IB unit?
A unit is interdisciplinary when students purposefully combine the concepts, knowledge, methods, or forms of communication of two disciplines to develop understanding that one discipline could not produce independently.
This differs from multidisciplinary teaching. Biology and Economics classes might both study water scarcity, but the work remains multidisciplinary if students produce separate ecological and economic responses. It becomes interdisciplinary when students integrate ecosystem evidence and economic models to evaluate a water policy.
| Approach | What students do | Example |
|---|---|---|
| Thematic | Encounter the same topic in different lessons | Both classes discuss water scarcity |
| Multidisciplinary | Produce separate disciplinary responses | Biology explains ecological effects; Economics examines pricing |
| Interdisciplinary | Integrate methods to reach a stronger conclusion | Students use ecological evidence and economic models to evaluate policy |
This distinction matters because mentioning the same topic does not automatically teach transfer. Students need explicit help comparing how disciplines define evidence, construct explanations, and handle uncertainty.
What the IB requires in the Diploma Programme
The IB's Programme standards and practices expects schools to provide collaborative planning time. Teachers should collaborate in curriculum design, consider relationships between areas, and reinforce shared concepts, content, and skills.
In the DP, collaborative planning and reflection should also support the integration of theory of knowledge into subjects. These expectations encourage cross-subject work, but they do not require DP schools to teach one formally assessed interdisciplinary unit every year.
That annual requirement belongs to the MYP, where students must participate in at least one collaboratively planned interdisciplinary unit involving at least two subject groups. DP teachers should therefore view interdisciplinary units as a valuable curriculum approach, not a separate compulsory DP assessment.
The DP nevertheless includes interdisciplinary opportunities. Under the updated extended essay for first assessment in May 2027, students may follow a subject-focused or interdisciplinary pathway. The interdisciplinary pathway integrates the lenses of two DP subjects.
A practical co-planning process
A manageable first unit usually involves two teachers, one shared inquiry, and a focused 2-3 week sequence. This allows time for disciplinary foundations, guided integration, and reflection without creating unnecessary timetable pressure.
1. Find a genuine connection
Start with each subject's current guide, required content, concepts, assessment objectives, and teaching sequence. Identify what students must learn even if the collaboration does not proceed.
Useful connections include:
- real-world problems, such as migration, food security, public health, or climate adaptation
- concepts, such as systems, power, representation, or sustainability
- methods, such as modelling, experimentation, textual analysis, or source evaluation
- transferable skills, such as interpreting data or evaluating limitations
Do not begin with a product such as a documentary or exhibition. First establish what each discipline helps students understand.
2. Test whether both subjects are necessary
Apply the removal test: Could students answer the inquiry well if one subject disappeared? If so, the connection is probably decorative.
A Biology and Economics unit might ask:
To what extent can market-based policies reduce antibiotic resistance without limiting equitable access to treatment?
Biology explains selection pressure, transmission, and resistance data. Economics examines incentives, externalities, information failure, and policy trade-offs. Students need both to reach a defensible judgment.
Teachers should complete this sentence: “Students need discipline A to understand ___, discipline B to understand ___, and integration to decide or explain ___.” If the final blank is unclear, revise the inquiry.
3. Define three kinds of outcomes
Separate the intended learning into disciplinary and integrative outcomes.
| Outcome type | Biology and Economics example |
|---|---|
| Biology | Explain selection pressure and interpret resistance data |
| Economics | Analyse market failure and evaluate interventions |
| Integrative | Use biological evidence and economic reasoning to recommend policy |
This protects disciplinary rigor because students cannot integrate ideas they do not understand. Teams should also select a few observable approaches to learning. “Evaluate the reliability and limitations of evidence” is more useful than listing the broad label “thinking skills.”
4. Design the synthesis task first
The final task should make integration unavoidable. Suitable formats include a policy brief, public hearing, comparative investigation, or evidence-based recommendation.
For antibiotic resistance, a policy brief could require students to explain the biological mechanism, interpret data, analyse stakeholder incentives, compare interventions, justify a recommendation, and identify scientific and economic limitations.
Teachers should not combine criteria from separate subjects into an unofficial IB grade. If the work contributes to subject grades, each teacher should assess only evidence that validly demonstrates their subject's outcomes under the current guide. A locally designed checklist can provide formative feedback on integration.
5. Sequence learning around dependency
Teach content in the order students need it rather than alternating subjects mechanically:
- Introduce the common problem and collect initial explanations.
- Teach essential disciplinary foundations.
- Compare evidence, assumptions, methods, and vocabulary in a bridge lesson.
- Analyse a partially integrated case with support.
- Complete the independent synthesis task.
- Reflect and conduct subject-specific follow-up.
The bridge lesson is crucial. Without explicit modelling, students often produce two adjacent mini-essays instead of an integrated argument.
6. Coordinate scaffolding and reflection
Use a one-page plan recording the inquiry, outcomes, sequence, responsibilities, vocabulary, accommodations, and deadlines. Terms such as model, validity, significance, and evaluation may mean different things across subjects. Comparing those meanings can create a natural TOK connection.
Scaffolds might include annotated data, vocabulary banks, structured sources, model paragraphs, and checkpoints. After teaching, review a sample of student work together and ask where students integrated both disciplines, where they merely placed ideas side by side, and what should change next time.
Making collaboration manageable
Different timetables, assessment calendars, and student combinations often create the greatest barriers. No student should depend on attending a course in which they are not enrolled. Concise disciplinary briefings or curated sources can provide necessary foundations, while assessment remains fair to different course combinations.
A realistic planning cycle includes two initial meetings, a short logistics check, and a post-unit review. School leadership should provide scheduled collaboration time, rather than relying entirely on voluntary lunchtime meetings.
Teachers can use RevisionDojo's IB resource hub and IB Questionbank to establish prerequisite subject knowledge. Its guidance on teaching for transfer and strengthening TOK connections can support shared planning without erasing disciplinary differences.
Common mistakes to avoid
- Choosing a broad theme: Replace “sustainability” with a specific, contestable problem or decision.
- Giving one subject a supporting role: Both disciplines must contribute necessary reasoning, not merely background information.
- Prioritizing presentation: Polished videos or posters can conceal weak understanding. Define evidence of learning first.
- Expecting automatic integration: Model comparison and synthesis before requiring independent work.
- Ignoring assessment calendars: Avoid clashes with internal assessments, mock examinations, and major coursework deadlines.
Conclusion
Effective interdisciplinary IB units begin with a question that genuinely requires two disciplines. Teachers then define disciplinary and integrative outcomes, design a synthesis task, sequence essential learning, and review evidence together.
In the DP, this approach supports collaborative planning, coherent curriculum design, shared skills, and TOK integration, but it is not the MYP's compulsory interdisciplinary unit. RevisionDojo resources, Study Notes, Questionbank practice, and Jojo AI can help teams prepare foundations, while its guides to collaborative teaching cultures and collaborative planning tools can support a repeatable process.
Sources and referenced URLs
- IB Programme standards and practices 2020
- IB research report on interdisciplinary learning
- IB guidance on MYP interdisciplinary study
- IB extended essay curriculum updates
- RevisionDojo IB resources
- RevisionDojo IB Questionbank
- RevisionDojo guide to teaching for transfer
- RevisionDojo guide to stronger TOK connections
- RevisionDojo guide to collaborative IB teaching cultures
- RevisionDojo guide to collaborative planning tools