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Lesson plan Grade 12 English Language Arts

What the Vinton Flats Water Notice Left Out

A 55-minute grade 12 lesson in which students judge what a utility's customer notice omitted, using its board memo and its own geosmin sampling record.

Objectives

  1. Students will explain how a technical memo and a customer notice select different details from the same water quality event.
  2. Students will integrate a data table with two prose sources to determine when complaints peaked and why.
  3. Students will write an explanatory paragraph that states the cause of the event accurately for a general reader.

Vocabulary

Key words: geosmin, taste-and-odor event, powdered activated carbon, verifiability, audience, explanatory writing

Teacher overview

Late in the summer, reservoirs often produce an earthy or musty flavor in finished drinking water, caused by compounds that algae and certain bacteria release as they die back. The water can meet every health standard and still taste wrong, which puts a utility in the position of explaining an aesthetic problem to people who reasonably read it as a safety problem. This lesson gives students the same event described twice, once in an operations memo written for a governing board and once in a customer notice posted online, and asks them to account for the differences. A misconception worth naming out loud is that the shorter customer notice must be concealing something because it omits the memo's detail; students should finish the lesson able to distinguish selection for audience from concealment, and to identify what genuinely was left out.

Procedure

Framing the situation (5 min): Tell students that a fictional utility, Vinton Flats Water Works, received an unusual number of complaints about the taste of tap water during one late-summer stretch. Explain that they will read two documents the utility produced about that stretch and a table of its own sampling results. Do not preview which document is more complete.

First read, the board memo (10 min): Students read the operations superintendent's memo on the handout and highlight in one color every sentence that names a measurement, a date, or a treatment action. Ask two or three students to read a highlighted sentence aloud and say what it commits the writer to.

Second read, the customer notice (10 min): Students read the customer notice and highlight in the second color every sentence that makes a claim about safety. Then have them mark each highlighted claim as one a reader could check against a measurement, or one a reader has to accept on the utility's word. Ask what the notice tells a reader to do, and what it leaves the reader unable to check.

Paired analysis of the data table (10 min): In pairs, students use the sampling table with both documents to answer handout items 5 through 8. Circulate and press pairs to say which document a given number came from, since the notice reports none of them.

Formative check (5 min): Poll the class on one question: does the customer notice contradict the memo, or select from it? Ask for a show of hands, then call on one student from each side to justify the choice using a specific sentence. If more than a third of the class answers "contradict," pause and re-read the notice's safety sentence against the memo's finding before continuing.

Explanatory paragraph (12 min): Students draft the paragraph described in handout item 10, explaining the cause and course of the event for a reader who has seen neither document. Remind them that an explanatory paragraph reports rather than persuades, and that every number they use must be traceable to the table.

Closure (3 min): Collect the paragraphs. Name the distinction the lesson rests on: a document written for a different audience selects different content, and selection becomes concealment only when the omitted content would change what a reader decides to do.

What the Vinton Flats Water Notice Left Out — Grade 12 English Language Arts
Name: ____________________________ Date: ______________

Student Handout

Vinton Flats is a fictional town, and every document below was written for this lesson. Read both documents and the sampling table, then answer the questions.

Document A. Memo to the Board of Water Commissioners, Vinton Flats Water Works

The earthy flavor reported by customers between August 14 and August 29 originated in Estabrook Reservoir rather than in the distribution system. Our taste-and-odor panel first identified the flavor on August 15, when the raw water sample reached 9 nanograms per liter of geosmin, a compound released by blue-green algae as a bloom breaks down. Geosmin is detectable by taste at concentrations far below any level associated with health effects, and no health-based standard applies to it. Beginning August 16, the plant fed powdered activated carbon at 12 mg/L ahead of the rapid mix basin, increasing to 22 mg/L on August 21 when raw geosmin peaked. Filtered water turbidity remained at or below 0.1 NTU throughout, and the chlorine residual leaving the plant held between 1.1 and 1.4 mg/L. Complaint volume fell sharply after August 24. Carbon feed at this rate carries a chemical cost the current budget did not anticipate, and staff recommend the Board consider a standing allowance for late-summer carbon.

Document B. Notice posted to the Vinton Flats Water Works website, August 18

Some customers have told us their water tastes or smells earthy this month. We have tested the water, and it is safe to drink. The taste comes from a natural compound that forms in our reservoir in warm weather. It is not harmful, and it does not mean the water is contaminated. Our operators have adjusted treatment at the plant, and the taste should fade over the next several days. Chilling water in the refrigerator, or adding a slice of lemon, may make the flavor less noticeable. Thank you for your patience.

Sampling and complaint record, Estabrook Reservoir and Vinton Flats plant

Date Raw geosmin, nanograms per liter Carbon dose, mg/L Customer complaints logged
Aug 14 6 0 4
Aug 15 9 0 19
Aug 17 14 12 41
Aug 21 21 22 63
Aug 24 11 22 22
Aug 29 5 8 3
  1. State the central purpose of Document A in one sentence, then state the central purpose of Document B in one sentence.
  2. Document A names the source of the flavor precisely. Quote the phrase it uses, and quote the phrase Document B uses for the same thing.
  3. Both documents explain why the water tastes earthy. Rank the two explanations by how much of each a reader could verify independently, and name the specific feature of each explanation that decides its place.
  4. Document A states that no health-based standard applies to geosmin. Explain how that sentence supports Document B's claim that the water is safe to drink, and what it does not establish.
  5. Using the sampling table, name the date on which raw geosmin was highest, and give that value.
  6. Using the sampling table, describe the relationship between raw geosmin and the number of complaints logged.
  7. Document B was posted on August 18. Using the table, explain why a reader who saw only the notice would have been surprised by what happened over the following three days.
  8. Name one fact reported in Document A that does not appear in Document B, and judge whether leaving it out would change what a customer decides to do. Support the judgment.
  9. Document A closes with a budget recommendation. Explain why that sentence belongs in a memo to a governing board and would be out of place in a customer notice.
  10. Write one explanatory paragraph of six to eight sentences for a reader who has seen neither document. State what caused the taste, what the utility did about it, when the problem was worst, and when it ended. Use at least two values from the table, and do not argue for or against the utility.

From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.

Answer Key
  1. Answer: Document A reports the cause, treatment response, and cost implication of the event to a governing board that must make a budget decision; Document B tells customers that the water is safe, explains the taste in general terms, and asks for patience.
  2. Answer: Document A calls it geosmin, a compound released by blue-green algae as a bloom breaks down. Document B calls it a natural compound that forms in our reservoir in warm weather.
  3. Answer: Document A's explanation is the more verifiable of the two. It names a specific compound, geosmin, gives its source in a blue-green algal bloom, and reports a measured concentration on a stated date that a reader can check against the sampling record. Document B names no compound and no measurement, describing only a natural compound that forms in warm weather, which a reader has no way to confirm or dispute.
  4. Answer: It supports the safety claim because geosmin is treated as an aesthetic problem with no enforceable health limit, so a strong taste does not mean a health limit was exceeded. It does not by itself establish safety, since having no standard is not proof that a compound is harmless, and it does not establish that nothing else in the water was elevated or say how long the taste would last.
  5. Answer: August 21, at 21 nanograms per liter.
  6. Answer: Complaints rise and fall with raw geosmin across the record. Every date fits: ranked by geosmin, complaints rise at each step.
  7. Answer: The notice went out on August 18 and told customers the taste should fade over the next several days, but raw geosmin rose to its highest value on August 21 and complaints reached their peak that same day, so the taste got worse before it improved.
  8. Answer: Accept any fact present only in Document A, such as the carbon dose, the turbidity result, the chlorine residual, the complaint counts, or the budget recommendation. A strong judgment argues that most of these would not change a customer's behavior because the water was safe either way, while a defensible opposing judgment notes that a customer told the taste would fade in days might have chosen differently had the notice reported that geosmin was still climbing.
  9. Answer: The board sets the utility's budget, so a recommendation to fund late-summer carbon is a decision that body must actually make. A customer notice asks readers to do nothing but wait, and a spending request would give them no action to take while implying the response depended on money not yet approved.
  10. Answer: Accept any accurate explanatory paragraph that reports rather than argues, names blue-green algae in Estabrook Reservoir as the source, states that the plant fed powdered activated carbon in response, identifies August 21 as the worst day, and marks the end of the event near August 29. It must include at least two table values, such as the peak of 21 nanograms per liter and the peak carbon dose of 22 mg/L, and it should not include a claim of fault.

Differentiation

Support

Give these students the two documents with the sentences already numbered and a two-column chart labeled "states a measurement" and "makes a general claim," so the sorting work is done before the comparison work begins. Allow items 1 through 4 to be answered in phrases rather than sentences, and provide the first sentence of the item 10 paragraph as a starter.

Extension

Ask students to draft a revised customer notice that keeps the reading level and length of Document B while adding whatever information they argued in item 8 that customers needed. They must then write two sentences defending each addition against the objection that it would alarm readers without changing what anyone could do.

ELL supports

Pre-teach "verify," "audience," "residual," and "aesthetic" with a short definition and one non-water example for each, and provide a sentence frame for item 3: "Document ___ can be checked because it gives ___, while Document ___ cannot because it gives ___." Allow students to answer items 5 and 6 by pointing to rows in the table and reading the values aloud before writing them.