Overview
The best IB ESS individual investigation asks a focused environmental question you can answer with data you gather or source, and then discusses it through the systems-and-sustainability lens ESS is built on. The IA is an independent investigation (confirm the current word range and weighting in your *ESS guide*) that you design, carry out, and evaluate. This post gives example research questions by area and shows how to sharpen a broad interest into a workable investigation. For the full write-up on criteria and structure, see the [IB ESS IA guide](/blog/ib-ess-ia-guide).
What makes a strong ESS investigation
This section covers What makes a strong ESS investigation — what IB examiners reward most often in past papers and coursework.
- Focused — one clear independent variable and one dependent variable, or one clear comparison.
- Measurable — data you can actually collect or reliably source (primary fieldwork, lab work, or credible secondary data).
- Environmental and systemic — it connects to ESS concepts (systems, flows, sustainability, human impact), not just a science experiment.
- Manageable and safe — a site you can reach, equipment you have, and a sensible risk assessment.
Example research questions by area
For the IB Diploma Programme, treat these as starting points — your site, data, and angle must be your own.
Ecosystems and biodiversity
- How does distance from a footpath affect plant species diversity, measured with quadrats along a transect? Trampling is a clear human impact and a diversity index gives real analysis.
- How does light or canopy cover affect the abundance of a species across a woodland gradient?
Water and pollution
- How does water quality (turbidity, nitrate, dissolved oxygen) change downstream of a potential pollution source?
- How does distance from a road affect a measure of air or soil quality near a school or park?
Soil and land use
- How does soil moisture or infiltration rate differ between land uses (grass, bare, compacted)?
- How does soil pH vary with distance from a specific source and what does it imply for the ecosystem?
Sustainability and human systems
- A footprint or resource-use comparison using survey or household data, discussed against sustainability concepts.
- Comparing a sustainability indicator between two contexts using credible secondary data, with evaluation of the data's limits.
How to turn an interest into a question
Narrow in three moves: pick a reachable site or a credible data source; choose one thing to change or compare (IV) and one to measure (DV) — so "pollution is bad" becomes "how does nitrate concentration change downstream of the outfall"; and connect it to ESS concepts so it reads as environmental systems, not a bare experiment.
Planning your investigation on MarkScheme
Lock in your question and method before fieldwork, and note limitations as you go. Use the free [ESS course](/ib/courses/environmental-systems-and-societies-sl) to ground the investigation in syllabus concepts, review [ESS past papers](/ib/past-papers/environmental-systems-and-societies-sl) for written-paper technique, and [get an answer marked](/mark) to keep exam skills sharp alongside the IA.
Frequently asked questions
This section covers Frequently asked questions — what IB examiners reward most often in past papers and coursework.
Can I use secondary data?
Yes, if it is credible and you evaluate its limitations. Many strong ESS investigations combine primary fieldwork with secondary data — but confirm the requirements in your current guide.
Does it have to be fieldwork?
Not necessarily — lab-based and data-based investigations are valid, provided the question is genuinely environmental and analysed through ESS concepts.
How long should the ESS IA be?
Confirm the current word range in your ESS guide. Whatever it is, a focused question you can answer fully beats a broad one you can only skim.