The Capacity to Do Simple Calculations is an Essential Part of Environmental Science

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Hello APES Teachers!


This is the first of what we hope will be occasional blog posts from Rick Relyea and me.


Rick and I are almost always working on our book, making revisions for the next printing or preparing a new edition. We love hearing from teachers about their successes and challenges. And we are always open to suggestions for improving our book.


Teachers often tell me that they want their students to have the best possible comprehension of environmental science topics and they also want them to build the skills they need to do well on the AP® exam. I always tell them that they can do both at the same time by focusing on analytical skills.


One of the chief readers for the APES exam a few years back used to say that a stellar student, possessing great factual knowledge of environmental science, could earn a 5 only if the student also possessed the ability to apply analytical reasoning to a problem. It is essential for every APES student to know how to read a story or graph or diagram and extract a few numbers, manipulate them mathematically to calculate an answer or generate a graph, and to produce a conclusion or finding. We’re talking about unit conversions, dimensional analysis and relatively easy addition, subtraction or division. These analytical skills are absolutely necessary for a full understanding of environmental science and for success on the APES exam.


Here’s an example: It’s a hot summer day. You live 100 miles from a nice, sandy beach. Which is less harmful to the environment? Stay at home and run an air conditioner for 8 hours that uses about 500 watts for 30 minutes of every hour? Or, drive 100 miles each way in your Toyota Prius?  


There are many ways to answer this question. If you were to do a calculation, you might determine the energy each activity used and conclude that whichever activity uses less energy will be less harmful to the environment.


Or, you might first calculate the gasoline used to drive to the beach and back, and calculate the carbon dioxide emissions from that activity. Then, assuming you turn your air conditioning off when you’re out, you might compare the carbon dioxide emissions generated by your trip to the emissions generated if you stay home all day and run your air conditioner. But to make this calculation, you would have to know how the electricity you are using is generated. If it is all generated by wind or solar, you might conclude that there is little or no carbon dioxide released from staying home and running your air conditioner.


So this seemingly simple question about a day at the beach versus a day at home is actually quite complex. There is no single “correct” answer. And that’s the point. We want our students to understand the issues, to feel comfortable with extracting information from a story or graph, to be able to conduct some sort of analysis with that information. There may not be one single correct answer. We want our students to have a grasp of the breadth and depth of the subject areas and factual material. But it is also essential for them to have a full appreciation of an issue, not just a reflexive, “gut call” on whether or not an action or a choice is “good” for the environment.


How do you teach your students this skill? Practice. Lot’s of practice. If you can take stories from the news or real-life examples from your school, your home or your community, that might interest and motivate your students. And our textbook, Friedland and Relyea’s Environmental Science for AP® is also a great place for numerous examples of word, graph and analytical problems to give your students practice.


Do you have a favorite problem you like to give your students? Let me know.



Andy Friedland

Dartmouth College

1 November 2017

Environmental Science for the AP® Course