Lesson plan Grade 9 English Language Arts
Pennistone's PFAS Notice: Writing a Public Explainer
A 55-minute grade 9 informative-writing lesson where students turn a fictional water district's PFAS test results into a clear public explainer for residents.
Objectives
- Students will write an informative paragraph that explains a technical water-quality result to a non-expert audience.
- Students will select and define key terms so a general reader can understand what a contaminant level means.
Vocabulary
- PFAS
- A large family of human-made chemicals used in things like nonstick pans, waterproof fabric, and firefighting foam. They are called forever chemicals because they take a very long time to break down.
- Contaminant
- A contaminant is anything in water that should not be there, whether it is a germ, a chemical, or too much of a natural mineral, that could make the water unsafe or unpleasant to use. Treatment plants are built specifically to find and remove contaminants before water reaches the tap.
- Maximum contaminant level (MCL)
- A maximum contaminant level, or MCL, is the highest amount of a certain substance that federal rules allow in drinking water. Water systems test regularly to prove their water stays under each limit.
- Parts per trillion
- A unit for measuring extremely small amounts of a chemical in water. PFAS limits are set in parts per trillion because these chemicals matter even in tiny doses.
Also: explainer
Teacher overview
When a water utility finds a contaminant, it has to explain the result to residents who did not study chemistry. This lesson uses a fictional utility, the Pennistone Water District, to give students a real informative-writing task: take a set of PFAS test results and write a short explainer that a worried resident could actually understand. Informative writing at this grade depends on selecting the right details and defining terms so a reader who knows nothing about the topic finishes the paragraph knowing what the result means and what happens next.
Procedure
Hook (8 min): Project the phrase "PFOA and PFOS detected at 4.0 parts per trillion" with no other context. Ask students to write for two minutes about what a resident reading only that phrase would still not understand. Collect two or three responses aloud. The point is that a true statement can still fail its reader, which is the problem informative writing solves.
Mini-lesson (12 min): Teach three moves that separate a clear explainer from a data dump: define each technical term in plain words the first time it appears; give the reader a reference point for any number ("parts per trillion" means a few drops in an enormous volume); and end with what the reader should do or expect. Model the first two moves using one sentence about PFAS, thinking aloud as you revise it from technical to clear.
Read the source (10 min): Distribute the Student Handout. Students read the Pennistone test results and the background on federal PFAS rules silently, underlining any term a general reader would not know. In pairs, they compare underlines and agree on the three terms most in need of a definition.
Draft (15 min): Each student writes one informative paragraph, roughly six to eight sentences, addressed to Pennistone residents. It must define PFAS, state what was found and how it compares to the federal limit, and tell residents what the district is doing. Remind students to write for a reader who is anxious, not for a chemistry teacher.
Peer check (7 min): Partners trade drafts and mark the paragraph against a three-point check: Is every technical term defined? Is at least one number given a reference point? Does the paragraph end with a clear next step? Each reader states one specific sentence that could be clearer. This is the formative checkpoint; circulate and read at least four paragraphs against the same three points.
Closure (3 min): On an exit slip, each student writes the single sentence from their own draft they think a resident would find most reassuring, and why. Collect to gauge whether students understand that clarity, not reassurance for its own sake, builds trust.
Student Handout
Your task: You write for the fictional Pennistone Water District. Residents received a postcard saying PFAS were "detected," and the office phones have not stopped ringing. Write one informative paragraph for the district website that explains the result plainly.
What the district measured (fictional scenario): Pennistone tests its wells for PFAS, a group of long-lasting industrial chemicals sometimes called "forever chemicals" because they break down very slowly. One well, drawn from near an old fabric-coating plant, showed a fictional PFOA level of 18 parts per trillion. The district blended that well with cleaner sources at first and has since shut it down for treatment.
What the rules say (real background): The federal maximum contaminant level for the PFAS chemicals PFOA and PFOS is 4.0 parts per trillion each. The rule was set in 2024, and water systems must meet the limits by April 2029. In May 2026, EPA proposed letting eligible systems apply for a two-year exemption, to April 2031; the limits would not change, and the proposal was not yet final as of September 2026. A "maximum contaminant level" is the highest amount of a contaminant that water is allowed to contain under federal law.
Write your paragraph so that it: defines PFAS and "maximum contaminant level"; states what Pennistone found and how it compares to the federal limit; gives the reader a reference point for how small "parts per trillion" is; and closes with what the district is doing and what residents can expect next.
From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.
Differentiation
Support
Provide a paragraph frame with four labeled sentence slots (define the term, state the finding, compare to the limit, state the next step) and a short word bank of plain-language substitutes for technical terms. Allow students to draft in the frame before writing a connected paragraph.
Extension
Ask students to write a second, shorter version of the explainer for a text-message alert of no more than forty words, forcing them to decide which single definition and which single number matter most. Have them justify what they cut.
ELL supports
Pre-teach "contaminant," "detected," and "maximum contaminant level" with a simple visual showing a small amount dissolved in a large tank. Permit students to write the first draft in a mix of home language and English and to translate the technical terms last, with a bilingual glossary card available.
Extensions
Invite students to compare their explainer to a real consumer confidence report, which every US water utility must publish each year, and to mark one place where the official document could be clearer for an ordinary reader. The comparison turns the lesson's writing moves into a tool for reading public documents critically.