Paper 1: the unseen case study

Paper 1 tests whether you can apply ESS knowledge to a place you have never studied. You are given a resource booklet about one unfamiliar location or issue, full of maps, graphs, tables, diagrams, photographs and short texts, and every question is based on it. Nothing in the booklet needs to be memorised in advance. What is tested is your ability to read data accurately, link it to ESS concepts and models, and make supported judgements about the place.

Because the place is unseen, Paper 1 rewards skills more than recall. Students who have practised describing trends, calculating from data, drawing systems diagrams and weighing up management strategies on unfamiliar material usually do well, even if the place is in a part of the world they have never studied.

How Paper 1 works

• The paper is an unseen case study: one place, ecosystem or issue, presented in a resource booklet with data in many forms.

• All questions are compulsory. There is no choice, so every part of the course could be drawn on, although each paper focuses on the topics that fit its case.

• Questions are based on the analysis and evaluation of the data in the booklet. Most ask you to use a specific figure or table, and the markscheme gives marks for quoting from it.

• The paper is worth 35 marks at SL and 70 marks at HL. The HL paper has the same format at twice the length.

• It is marked with a question-specific markscheme: each question has its own list of acceptable points. There are no markbands.

• A calculator is needed for calculations such as percentage change, rates, indices and doubling times.

• Questions typically build from short items worth 1–2 marks (identify, state, calculate, describe) to longer ones worth 3–4 marks (explain, suggest, distinguish) and end with one or more extended questions that ask you to evaluate, discuss or justify a strategy for the place.

The paper tests three assessment objectives. AO1 questions check that you know the concepts and terms; AO2 questions ask you to apply them to the data; AO3 questions ask you to explain, evaluate and justify. Because almost every question asks you to work with the resources, most of the paper tests application, analysis and evaluation rather than recall.

The video is an ESS teacher’s overview of how to approach the resource booklet and the question types in the current Paper 1.

YouTube

What a resource booklet contains

A booklet presents one place through several types of resource. Each type needs a slightly different way of reading. The table lists the common ones and what to look for in each.

How to read the booklet

There is no single right way to work through a booklet, but students who read actively, with a pencil, find the answers faster and miss less. A routine that works for most students is set out in the steps.

1. Skim the questions first. Knowing what you will be asked tells you what to look for in the resources.

2. Read the introduction and fact file closely. Note the place, its system (lake, forest, city, coast), the main problem, the stakeholders and any strategies proposed.

3. Annotate each figure. Write the overall trend beside every graph, circle the highest and lowest values, and mark anomalies. Note any link to another resource (“land clearing in Figure 3 → turbidity in Table 1?”).

4. Label the ESS concepts you can see. Write the concept beside the evidence: “eutrophication”, “invasive species”, “tragedy of the commons”, “positive feedback”, “ecocentric”.

5. Answer in order, but keep the final evaluation question in mind. Evidence you find for short questions is often the evidence the last question needs.

Question types and how to answer them

The same handful of question types appears on almost every Paper 1. Each has a recognisable shape and a way of earning full marks.

A worked mini case study: Lake Melora

The booklet describes a tropical highland lake whose fishery, water quality and surrounding land have changed quickly since 2000. Read all the resources first, annotating as you go, then attempt each question before opening the model answer.

Resource 1: fact file

• Lake Melora is a freshwater lake at 1,600 m above sea level in a tropical highland region. Area 620 km²; mean depth 9 m. The Kaso River is its main inflow; the Ashani stream drains a forest reserve on the eastern hills.

• About 410,000 people live in the catchment (2024). Most farm small plots of maize, beans and coffee. Since 2005, flower farms on the west shore have grown roses in greenhouses for export, using lake water for irrigation.

• Nile tilapia (Oreochromis niloticus) was introduced to the lake in 1996 to increase fish catches. Native cichlid fish are endemic: they are found nowhere else.

• Registered fishing canoes: 410 in 2000; 1,150 in 2024. Total fish catch: 9,200 tonnes in 2000; 7,200 tonnes in 2024.

• Water hyacinth (Pontederia crassipes, formerly Eichhornia crassipes), a floating plant from South America, was first recorded in the lake in 2011. In 2024 it covered 14% of the lake surface.

• Melora town’s sewage receives primary treatment only. About 60% of households are connected to the sewer.

• Strategies proposed in the district’s 2025 lake plan: (1) a closed fishing season of three months each year in the breeding bays, with a minimum net mesh size; (2) buffer strips of native trees 20 m wide along the Kaso River; (3) secondary and tertiary sewage treatment for Melora town; (4) biological control of water hyacinth with weevils, plus mechanical harvesting of the mats for compost; (5) payments to Ashani forest communities for protecting the forest.

Resource 2: map of the catchment

Resource 3: fish catch, 2000–2024

The district fisheries office records the annual catch landed at the lake’s landing sites.

Resource 4: land cover in the catchment

Land cover was mapped from satellite images in 2000 and 2024.

Resource 5: water quality and population

Table 1. Water quality at the three sites on the map, measured in the dry season of 2024, with the district’s target values (invented data).

Table 2. Population of Melora town, from national censuses and a 2024 estimate (invented data).

Resource 6: stakeholder statements

The statements were collected at a public meeting on the 2025 lake plan (invented statements).

Resource 7: a systems diagram

Questions and model answers

Each question below is followed by a model answer and the marking points it would earn. Try every question yourself first. Marks are in square brackets.

Question 1: reading the map and graph

Question 2: fishing effort

Question 3: water quality and land use

Question 4: the systems diagram

Question 5: population growth

Question 6: water hyacinth

Question 7: explaining a decline

Question 8: perspectives

The final evaluation question

Most Paper 1s end with a longer question that brings the whole booklet together. It is usually the single part worth the most marks, and it is where the strongest answers pull ahead. The question for the Lake Melora booklet is given in full, followed by a weak and a strong answer and how each would be marked.

Covering every strategy is not always necessary. If time is short, two or three strategies evaluated in depth, with evidence and a judgement, usually score better than five strategies each given one line.

Common mistakes on Paper 1

Examiners see the same errors every session. Most cost one or two marks each, but across a whole paper they add up to a large share of the marks.

A related error is reading the wrong series. When a graph has two lines or a table has several columns, put a finger or a ruler on the right line before reading a value, and name the series in the answer.

Generic answers are the third common problem. A suggestion such as “the government should educate people” could apply anywhere and earns little. Make it specific to the place: who should be educated about what, and why the resources show it is needed.

How SL and HL papers differ

The SL and HL Paper 1s have the same format: one unseen case study, a resource booklet and compulsory questions marked with a question-specific markscheme. The HL paper is twice as long, with twice the marks, so it has more questions on the booklet and may include more resources and more extended questions.

HL students study additional content in most topics and the three HL lenses (environmental law, environmental economics and environmental ethics). An HL booklet may give the chance to use that material, for example by naming the legal status of a protected area, using an economic tool such as payments for ecosystem services, or discussing the intrinsic value of an endemic species. Bringing a lens in where it fits, briefly and accurately, strengthens an evaluation.

Preparing for Paper 1

Paper 1 cannot be revised by learning a case study, so preparation means practising the skills on unfamiliar material. Three habits make the most difference.

1. Practise on real data from unfamiliar places. Take a graph or table from a news article, an agency report or a data site, and ask yourself the standard questions: describe the trend, calculate the change, suggest reasons, evaluate a response.

2. Build a concept bank. For each topic, list the concepts and models that explain patterns in data: eutrophication, biomagnification, the tragedy of the commons, maximum sustainable yield, positive and negative feedback, succession, the demographic transition, the pollution management model. In the paper, these are the words that turn a description into an explanation.

3. Rehearse the final question. Practise writing six-mark evaluations under time pressure, using evidence from several resources and ending with a judgement.

Key points

• Paper 1 is an unseen case study: every question is based on a resource booklet about one unfamiliar place.

• All questions are compulsory and marked with a question-specific markscheme; they move from short data questions to extended evaluation.

• Read the title, axes, units and key of every figure before the data, and annotate the booklet as you read.

• Quote values with units, name the figure, and link the evidence to ESS concepts in every answer.

• Describe questions want values, not reasons; explain questions want a chain of causes tied to the resources.

• Suggest and evaluate answers must fit the place in the booklet, not a case study learned in class.

• The final question rewards evidence from several resources, more than one perspective, strengths and limitations of each strategy, and a clear judgement.

• The HL paper has the same format at twice the length; HL lenses can strengthen evaluations where they fit.