AP® Environmental Science Course And Exam Description

In AP® Environmental Science, you’ll dive deep into environmental concepts to understand the environment, tackle issues and challenges associated with it, and come up with smart solutions to address those problems. These solutions will include scientific methods that affect our environment and society.

The AP Environmental Science course is equivalent to a one-semester, introductory college course1 on the subject. If you’re planning to take the APES course and exam, it is important to familiarize yourself with its course content.

In this easy-to-understand course and exam description guide, we'll break down the APES course outline, talk about the units and topics tested, and explore the key concepts you'll be mastering. This will help you prepare a thorough study plan and make your exam prep hassle-free.

AP Environmental Science Units, Topics and Key Concepts

The APES course is made up of two components:

  1. Course Content, and
  2. Its associated Science Practices

The course content is divided into 8 widely taught units. These units are connected to each other with overlapping themes, called big ideas. There are four big ideas in the course, which we will explore soon. In addition, the course covers 7 types of science practices, which you’ll acquire as you journey through these units. Let’s start with the big ideas first, and then we’ll move on to the course units and skills.

AP Environmental Science’s Four Big Ideas

The big ideas are the basis of the course and help students make connections between course units and concepts. Students can get a deeper understanding of the big ideas by applying them in different ways as they go through each unit. Listed below are the big ideas2 for the APES course, with a short description of each:


    Energy transformations drive all ecological processes. Energy cannot be created; it can only change forms from one type to another (eg.: from potential to kinetic energy). As energy passes through systems, a greater proportion of it is wasted at each step.

    The Earth is made up of interconnected biochemical systems that work together to create the stable ecosphere we call “earth”. These individual systems change over time and space, and each system has a different threshold for recovering from damage or disturbances.

    For millions of years, humans have altered Earth’s natural systems, which have had an enormous impact on the environment. The nature and pace of this impact have grown exponentially with the development of technology and population growth.

    To survive and thrive, we need sustainable systems. That means finding the perfect balance between conserving and developing resources. Managing our resources wisely is super important. As we work towards developing solutions, we need to understand that cultural, social, and economic factors play a big role in finding solutions.
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Diagrams showing how greenhouse gasses accumulate impact the Earth’s global warming potential.

AP Environmental Science’s 9 Units and Their Topics

As you may already know, the big ideas we discussed above spiral through the 9 course units of APES3. As you go through the course, you’ll realize that one or more of these big ideas reappear in each unit. Although there are 9 units in the course, some units have more weight than others, especially in the multiple-choice section. This means that you’ll get more questions from these units compared to others. The table below lists the units and their respective weights in Section I of the exam:

Units Weighting
Unit 1: The Living World: Ecosystems 6–8%
Unit 2: The Living World: Biodiversity 6–8%
Unit 3: Populations 10–15%
Unit 4: Earth Systems and Resources 10–15%
Unit 5: Land and Water Use 10–15%
Unit 6: Energy Resources and Consumption  10–15%
Unit 7: Atmospheric Pollution 7–10%
Unit 8: Aquatic and Terrestrial Pollution 7–10%
Unit 9: Global Change 15–20%

If you want to learn more about any of the AP Environmental Science units, you can click on the unit widgets below:

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What Are the Science Practices for the AP Environmental Science Course

The AP ES science practices explain the skills a student should acquire during the course and be able to execute in the exam. Listed below are the 7 skill categories that you should master by the end of your APES course. Note that questions on the exam will ask you to solve problems by using one or more of these science practices4.

Science Practice 1: Concept Explanation

You’ll learn to explore environmental concepts, processes, and models in written form. 

You will learn how to:

  • Describe and explain environmental concepts and processes in applied contexts.

Science Practice 2: Visual Representations

You’ll learn to explore visual representations of environmental concepts and processes.

You will learn how to:

  • Describe and explain how the visual representation of an environmental concept, process, or model relates to broader environmental challenges.

Science Practice 3: Text Analysis

This science practice will help you analyze sources of information about environmental issues.

You will learn how to:

  • Define the author's point of view.
  • Describe the author's viewpoint, assumptions, and reasoning.
  • Analyze the reliability of a source and assess the soundness of a study's findings.

Science Practice 4: Scientific Experiments

The fourth science practice will teach you how to analyze research studies that focus on environmental principles.

You will learn how to:

  • Find a hypothesis or scientific question prior to conducting an investigation.
  • Specify the methodology, design, and/or measurement employed.
  • Describe an aspect of the employed study method, design, or measure.
  • Observe laboratory settings or collect data from them.
  • Describe alterations to a procedure that will affect the results.

Science Practice 5: Data Analysis

You’ll learn to analyze and interpret quantitative data presented in tables, charts, and graphs.

You will learn how to:

  • Describe data-based patterns.
  • Describe connections between variables represented in data.
  • Explain data trends and patterns to draw a conclusion.
  • Analyze experimental data and outcomes in light of the specified hypothesis.
  • Explain what the evidence suggests or indicates regarding environmental concerns.

Science Practice 6: Mathematical Routines

The sixth science practice will teach you how to use quantitative methods to talk about ideas about the environment.

You will learn how to:

  • Identify a strategy or method that corresponds to the problem to be tackled.
  • Utilize relevant mathematical relationships, such as dimension analysis, to solve an issue.
  • Calculate a precise numerical answer using the correct units.

Science Practice 7: Environmental Solutions

You’ll learn how to identify solutions to environmental problems.

You will learn how to:

  • Describe and explain environmental problems.
  • Describe potential solutions or methods for environmental issues.
  • Describe downsides, advantages, or unforeseen consequences for suggested solutions.
  • Use info and evidence supporting a prospective solution.
  • In an applied context, make a claim that provides a remedy to an environmental issue.
  • Clarify a suggested solution by describing its potential benefits.

Frequently Asked Questions

The AP Environmental Science course has 9 units. Each unit is divided into teachable segments known as “topics.” Each unit has approximately 10 topics.

The top 5 units carrying the most number of questions on the APES MCQ section can be considered more important than other units. These units are listed below:

  1. Unit 9: Global Change (15–20%)
  2. Unit 3: Populations (10–15%)
  3. Unit 4: Earth Systems and Resources (10–15%)
  4. Unit 5: Land and Water Use (10–15%)
  5. Unit 6: Energy Resources and Consumption (10–15%)
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Illustration of how species richness and biodiversity benefits ecosystems.


1(2024). College Course Equivalent. Equivalency and Prerequisites. AP Environmental Science. College Board. Retrieved on March 11, 2024 from

2(2019). Big Ideas. Course Content. AP® Environmental Science COURSE AND EXAM DESCRIPTION.  Retrieved on March 11, 2024 from

3(2024). Course Content. AP Environmental Science.  Retrieved on March 11, 2024 from

4(2019). Science Practices. AP Environmental Science. Retrieved on March 11, 2024 from

Read More About the AP Environmental Science Exam

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