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Environmental Systems and Societies · Individual investigation

Eight steps to your ESS IA

The internal assessment (IA) is worth 25% of your grade at SL and 20% at HL.

You choose a real issue that somebody already measures, find out what their numbers show, and argue for what should be done.

Where your data comes from

Secondary data

Someone else collected it, you analyse it
What it looks like
Numbers somebody else has already collected and published, which you download and work on yourself. Water quality records, weather stations, satellite measurements, national statistics.
What it asks of you
Instructions clear enough that a stranger could download exactly the same file you did.
Where the difficulty is
Finding data that exists for the place and the years your question needs.
The scale you work at
Fifty years, or fifteen cities, or a whole river basin.
Start step 1
Alongside the stepsDatasetsWhat everything is calledTen starter investigations
What it is not

Secondary data does not mean writing about what other people found. A report that only reviews other people’s writing is not a repeatable method, and that alone holds Criterion C (Method) at the bottom band, however good the rest of the report is.

25%
of your grade at SL, 20% at HL
30
marks, across six criteria
3,000
word limit
10 hrs
of class time at most, plus your own time
The three lines

Every investigation in this guide has the same shape, and it runs one way: from what people do to what happens to nature, with somebody's plan acting on one of them. Steps 1 to 3 fill the three lines, and the rest of the guide tests them.

  1. 1What people doCriterion A

    Your independent variable is a column of what people do.

  2. 2What happens to natureCriterion A

    Your dependent variable is a column about a population, an ecosystem, a water body or the soil. One individual can do, named as a limitation.

  3. 3Somebody's planCriterion B

    A real plan changes what people do, protects what happens to nature, or is what people do. At the IB minimum it may act elsewhere, if its connection to the question is stated.

Lay yours out on the three lines and see where it stands, or open the starter investigations: ten that already pass.

Four words, used precisely

These four turn up on every page of the guide, in the checklists, and in the mark scheme. They mean the same thing each time, and in each case the everyday meaning of the word is the one that loses marks.

Issue
Not a topic. Something that is happening, to something, because of something, in a place you can name. “Deforestation” is a topic. “A national moratorium on clearing, and whether the clearing moved to the savannah next door” is an issue.
Real-world strategy
A plan that real people are actually carrying out about your issue: a law, a management scheme, a funded programme, a contract. Not what you think should be done, and not a general good idea like “more education”. If you cannot cite it, it is not one.
Tension
Two parties who both want something reasonable and cannot both have it. Not a disagreement about facts, and nobody has to be the bad side: the commune needs winter visitors, the nature reserve wants the forest back, and the same hectare cannot do both.
Dataset
The numbers you will analyse, as numbers rather than as a chart or a claim. A file you can change in a spreadsheet, covering the years and places your issue is about. A page saying the data exists is not a dataset.

The process

Each step produces something the next one needs. The word counts are what we suggest spending when you eventually write that section up, not what to write now.

1
Find your issue, and check it is measured
An environmental issue somebody already measures, and a sketch of the system
A
500
2
Write your research question
One sentence naming the indicator, its units, the years and the places
A
50
3
Find a real-world strategy and its tensions
A real-world strategy, two sourced positions, one explained tension
B
500
4
Select and document your data
The file you will actually use, counted, with a rule you fixed before looking
C
500
5
Treat your data
Raw data tabulated, your own figures, and a statistic. No interpretation yet
D
200
6
Analysis and conclusion
Every pattern explained through the system, and an answer your rows can carry
E
550
7
Evaluation
What your source could not tell you, ranked, and what you would use instead
F
600
8
Write it up
One report that reads as though one person wrote it
all
Total
30 marks
2,900

The IB sets no section word counts and no required order. These figures are ours, and so is the order.

What makes this an ESS investigation

Three ideas run through the course, and a strong report carries all three.

Systems

Your variable sits inside something with inputs, outputs, stores and feedbacks. Not a list of measurements.

Perspectives

People want things that clash, and what happens to an environment depends on how that conflict is settled.

Sustainability

Whether what is happening can continue, and who pays the cost.

How to use this guide

Work through the steps in order. Each one opens with what you should be arriving with and closes with a checklist: the only part that asks about your investigation rather than explaining things in general.

Tick honestly. A box you cannot tick yet is not a mark against you. It is simply the next thing to do. If you are signed in, your ticks are saved and your teacher can see how far along you are.

The checklists are gates
Not a review at the end. They tell you whether you are ready for the next step.
One example runs throughout
A real study followed from first idea to finished report.
We say where things come from
What the IB requires and what is our advice are labelled differently. The colour key below shows how.
What the colours mean
The standard
What the IB requires, and what a top-band answer looks like
The CDN approach
Beyond what the IB actually asks for
Falling short
Pitfalls, weak versions, and how a step goes wrong
The worked example
The running study, wherever it appears
The example that runs through all eight steps

The full study, the file it came from, and its real sources

One thing before you start

You will get one round of written feedback on a full draft. Your teacher can comment on what is strong and what is weak, but they cannot correct it, and there is no second draft after that.

So hand over something complete rather than something polished. If three sections are finished and five are missing, you only get feedback on three sections. And aim for 2,900 words rather than 3,000. The feedback will almost certainly ask you to develop something, and at 3,000 words the only way to do that is to delete something good.

Step 1 · Find your issue, and check it is measured

Most advice tells you to choose a topic. We think you should choose an issue somebody already measures, and step 1 explains how to find out whether they do.

Start step 1

The white shark investigation used on the secondary-data route of this guide is the author’s own analysis of a published dataset: the Queensland Shark Control Program’s record of every animal caught on its nets and drumlines, published by the Queensland Government under CC BY 4.0 and downloaded on 26 September 2026. The choice of the four areas, the analysis and the conclusions are the author’s, not the Queensland Government’s. It is written to show how an ESS investigation is built, not to report findings about shark control in Queensland.