Graphic organizer Grade 11 English Language Arts
Tracing the Cause Chain in the Marnholt Taste-and-Odor Report
A grade 11 cause-and-effect chain organizer that separates the links a technical report asserts from the links it only suggests, using a musty-water investigation.
Objectives
- Students will sequence the links of a causal chain stated across a technical report.
- Students will label each link with the strength of the cause language the report uses.
- Students will name the observation that would break a given link in the chain.
Vocabulary
- Activated carbon
- Activated carbon is a special charcoal full of microscopic holes that grab and hold chemicals as water flows past. It is the same material used in many home water filter pitchers.
Also: stratification, geosmin, bloom, causal chain, hedge
Teacher overview
This organizer is a linear cause-and-effect chain of six links, with two analytic columns beside each link: the strength of the cause language the source uses, and the observation that would break the link. Students often read a technical report as though every sentence in it carries the same force, so a sentence containing "is consistent with" gets copied into an essay as though it said "caused." Separating the asserted links from the suggested ones is the point of the cause-language column. The water content also carries a misconception worth naming aloud: an earthy or musty taste in tap water leads many people to conclude the water has become unsafe, when the compounds that produce that taste are detectable by the human nose and tongue at concentrations far below any level that would matter to health, and a utility investigating a taste complaint is usually investigating an aesthetic problem rather than a hazard.
Organizer
The text under study. A four-page taste-and-odor investigation written by the water plant staff for the town board. The town of Whitgrove, Marnholt Reservoir, and every figure below are fictional and were written for this organizer.
Excerpts from the report.
- Paragraph 2. "Surface temperature at the Marnholt intake rose through late July, and by August 4 the reservoir showed clear layering, with the warm upper layer no longer mixing with the colder water below."
- Paragraph 3. "Cell counts in the upper layer rose sharply during the same period. Warm, still conditions are consistent with this kind of increase, although we did not sample nutrient levels often enough to say what drove it."
- Paragraph 4. "Geosmin, a compound released by several kinds of algae, was measured at 22 ng/L in the raw water on August 7. The threshold at which a typical person notices it is far below that."
- Paragraph 5. "Geosmin is dissolved. It passes through our filters, which remove particles. Removing it requires powdered activated carbon, which we do not currently feed."
- Paragraph 6. "The customer service log recorded 41 musty-taste calls between August 8 and August 15, concentrated in the pressure zone served directly from the plant."
Laboratory table.
| Date | Raw water geosmin | Finished water geosmin |
|---|---|---|
| July 21 | 3 ng/L | 3 ng/L |
| August 7 | 22 ng/L | 21 ng/L |
| August 20 | 9 ng/L | 8 ng/L |
Directions. Fill one row per link. In the cause-language column write only "states," "suggests," or "cannot rule out," and give the words from the report that justify your choice.
| Link | The step, in your own words (arrow shows what it leads to) | Cause language the report uses | What observation would break this link |
|---|---|---|---|
| 1 | (write here) → | (write here) | (write here) |
| 2 | (write here) → | (write here) | (write here) |
| 3 | (write here) → | (write here) | (write here) |
| 4 | (write here) → | (write here) | (write here) |
| 5 | (write here) → | (write here) | (write here) |
| 6 | (write here) | (write here) | (write here) |
Last step. Circle the weakest link in the chain, which is the one where the report's language is furthest from "states." Then write one sentence that a careful writer could publish about that link without going beyond the report.
From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.
Completed Exemplar
| Link | The step, in your own words (arrow shows what it leads to) | Cause language the report uses | What observation would break this link |
|---|---|---|---|
| 1 | Late-July heat warmed the surface of Marnholt Reservoir until the warm upper layer stopped mixing with the cold water below. → | States. Paragraph 2 reports the layering as an observed condition. | A temperature profile from early August showing the same reading from surface to bottom. |
| 2 | Cell counts in that warm upper layer rose sharply over the same weeks. → | States for the increase, suggests for its cause. Paragraph 3 says warm, still conditions are "consistent with" the rise and admits the nutrient sampling was too thin. | Counts rising just as fast during a cool, windy stretch when the reservoir was mixing. |
| 3 | The algae in that layer released geosmin into the water. → | Suggests. Paragraph 4 identifies geosmin as a compound released by several kinds of algae but does not tie the August reading to a named organism. | Geosmin appearing in the raw water while cell counts stayed at their July level. |
| 4 | Geosmin reached the plant intake, where it was measured at 22 ng/L on August 7. → | States. The measurement is reported directly and the table repeats it. | A second laboratory finding a different result on a split sample from the same date. |
| 5 | Because geosmin is dissolved rather than suspended, the filters passed it through nearly unchanged. → | States. Paragraph 5 gives the mechanism, and the table supports it, since finished water tracked raw water within about one unit on all three dates. | Finished water reading far below raw water on a date when no carbon was fed. |
| 6 | Customers on the pressure zone fed straight from the plant tasted the compound and called, producing 41 complaints in eight days. | States for the calls, suggests for the taste being the cause of them. Paragraph 6 reports the count and the geography without ruling out another trigger such as a news story. | Complaints spread evenly across zones the plant does not feed directly. |
Weakest link, identified. Link 2 is the weakest, because Paragraph 3 admits the sampling was too thin to say what drove the rise. A defensible published sentence would read: cell counts in the upper layer rose during a period of warm, still weather, and the plant did not sample often enough to identify what caused the increase. Link 3 is also a defensible choice, since Paragraph 4 only places the geosmin reading beside the fact that algae release it and never ties the August reading to the bloom; accept either answer when the student cites the report's wording.
Differentiation
Support
Give these students the six links already written in scrambled order and ask them to sequence the links and complete only the cause-language column. Provide the three permitted labels on a printed strip and one worked example, using Link 1, so the distinction between an observed condition and an inferred cause is modeled before students apply it.
Extension
Ask students to write the chain a second time as it would appear in a two-sentence notice mailed to customers, then to list every link the notice had to drop and to defend one of those cuts in a short paragraph addressed to the plant manager.
ELL supports
Pre-teach "layering," "dissolved," "suspended," and "threshold" using a jar of water with sand and a jar with dissolved salt, so the filter mechanism in Link 5 is visible before it is read. Provide the three cause-language labels with a short paraphrase beside each, and allow the final column to be answered with a phrase beginning "if we saw."
Extensions
Have students find the one sentence in their own most recent explanatory essay that hedges, and rewrite the surrounding paragraph so the hedge is doing deliberate work rather than softening a claim the writer was unsure of. Ask them to name, in one sentence, what a reader gains from the hedge. Paragraph 3 of the Marnholt report is the model to work from, since its hedge tells a reader exactly what the sampling could not establish.