PFAS Guided Inquiry Activity

text: PFAS Guided Inquiry Activity over dark water and molecule of pfas

After the 2021 AP Test, I used the movie “Dark Waters” (see video 1) and this PFAS Analysis guided inquiry activity to introduce students to “Forever Chemical” pollutants in the environment (see figure 1). Students applied their knowledge about electronegativity, polarizability, and bond strength to PFAS molecules. I was able to see and help clarify student misconceptions that didn't come to light during my normal instruction. 100% of my students reported having a better understanding of IMFs after completing the assignment.

DARK WATERS | Official Trailer | In Theaters November 22

Video 1: Dark Waters official trailer, Focus Features You Tube Channel (accessed 3/24/2023). The film tells the story of an attorney (played by Mark Ruffalo) who uncovers a dark secret hidden by DuPont, one of the world’s largest corporations. (Available for paid streaming through Amazon Prime or Youtube.)


I wrote this activity for use in my AP Chemistry WE Service curriculum. WE ( is a non-profit organization focused on service learning. They teamed up with CollegeBoard’s AP program to award special certificates and scholarships to students who successfully complete a service-learning project in their AP classes. I had the opportunity to attend training and am in my second year of offering WE Service content. Read my post, AP Chemistry with WE Service, for more details about the program. There are two AP Chemistry service-learning modules offered by the AP with WE Service program - Incorporating Green Chemistry and Access to Clean Water. The activity described here was written for the second module.

Figure 1: Perfluoroctanoic acid is an example of a "Forever Chemical" and one of the molecular structures students consider in the activity.

environmental chemistry
intermolecular forces
Procedure time: 
90 minutes

Provide students with the following resources:

Student Handout

Molecule and Data Handout - Bond energy, electronegativity values and atomic radii data and molecular drawings (PFOA, Gen-X, Tris, TPHP, Soap-Like Molecule)

See the Supporting Information to access student and teacher documents. (Readers must log into their account to access. Not a member? Register for free!)


Introduce the topic: Many students have not heard about PFAS and have no prior knowledge to build off of on the topic. There are a wealth of PFAS videos online to help introduce the topic. There are longer documentaries like Dark Waters (paid streaming through Amazon Prime or Youtube) or The Devil We Know (free through Youtube - accessed 3/24/2023) you can show or shorter TV segments like CBS Sunday Morning’s “Forever Chemicals” (see video 2). It might be a good idea to search “PFAS” and your state to find PFAS videos on Youtube that contain local information. Be sure to select a video which introduces students to PFAS and does NOT explain the chemistry behind the behavior of PFAS. While watching the videos, students can answer Question #1 on their student handout by listing products they use that contain PFAS. 

Forever chemicals: The threat of PFAS in our water

Video 2: Forever chemicals: The threat of PFAS in our water, CBS Sunday Morning YouTube Channel (accessed 3/24/2023)


Collaborative group work: Once students know some basics about PFAS, help students form collaborative groups. Provide students with the data handout and the Soap-like and PFOA molecule handouts. Students should complete the “initial ideas” box with their groups. Student groups should make a claim, backed by evidence and reasoning from the data handout and their AP Chemistry knowledge of intermolecular forces and covalent bonds.

Student groups will present their ideas to their classmates during a full-class discussion. I like using whiteboards for presentations, but it is not necessary. The teacher will facilitate a class discussion about similarities and differences between initial ideas. The goal is not to be “right” as scientists are still learning more about how PFAS works, but rather to apply their AP Chemistry knowledge appropriately and reasonably. After discussion, students should refine their answers and complete the “revision” box. This process repeats for each question.

For question #5, handout the Gen-X, Tris, and TPHP molecule handouts to groups. In this question, students have to predict if the alternative molecule will behave higher, lower, or the same as the original PFOA molecule. Just like before, the goal is not to be “right” but rather apply their AP Chemistry knowledge in a reasonable way. After groups make their initial presentations, the class can discuss like before.

Wrap-up: The Youtube Channel “Reactions” has a great video to wrap up the class discussion as it covers some of the chemistry of PFAS (see video 3.)

Forever Chemicals

Video 3: Forever chemicals, ACS Reactions YouTube Channel (accessed 3/24/2023)


At the end of the video it mentions how microbes might help. Students can do a close read on this new research: Can microbes save us from PFAS? from Chemical & Engineering News and research other solutions, if there is time. Students can complete an exit ticket answering the questions:

  • What are Forever Chemicals?
  • Why are they dangerous? 
  • What should we do about it?

Benefit of this activity to my AP Chemistry students: The goal of this activity is to have students transfer their AP Chemistry reasoning and knowledge to a new and current topic, like PFAS. This activity is not meant to teach intermolecular forces or covalent bonding and is best completed after Unit 3, during your review before the AP test, or after the AP test. While taking time to transfer knowledge might seem important, I was surprised at how many misconceptions about intermolecular forces and bonding I was able to address. These misconceptions were not apparent to me as students completed traditional AP questions. By asking students to transfer their knowledge to new open-ended questions about PFAS, I was able to hear and see what students were really thinking and help bring clarity to their understandings about bonding and intermolecular forces. 


To save paper you can print out the required resources and laminate them for re-use or post them on your class website or learning management system. 


I learned a lot about the topics necessary to help me write this activity thanks to support I received on Twitter. Shout out to @Saskia_SvB@ShiraJoudan@dqasci@PFASactiongroup@mrfarabaugh, and @CummingsLinda!


Students who demonstrate understanding can plan and conduct an investigation to gather evidence to compare the structure of substances at the bulk scale to infer the strength of electrical forces between particles.

*More information about all DCI for HS-PS1 can be found at and further resources at


Students who demonstrate understanding can plan and conduct an investigation to gather evidence to compare the structure of substances at the bulk scale to infer the strength of electrical forces between particles. 

Assessment Boundary:

Assessment does not include Raoult’s law calculations of vapor pressure.


Emphasis is on understanding the strengths of forces between particles, not on naming specific intermolecular forces (such as dipole-dipole). Examples of particles could include ions, atoms, molecules, and networked materials (such as graphite). Examples of bulk properties of substances could include the melting point and boiling point, vapor pressure, and surface tension.

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Comments 1

James Grant | Tue, 04/04/2023 - 08:31

I'm working on a blended chemistry/biology semester-long credit recovery course in environmental science, and this would fit the bill perfectly for in-person students (I'll come up with something a bit more interactive for virtual students). Thanks!