Worksheet Grade 9 English Language Arts
Pronoun and Modifier Ambiguity in the Pelbrook Startup Memo
A grade 9 ELA worksheet on ambiguous pronouns and misplaced modifiers, using a fictional startup memo for a membrane treatment train where the ambiguity has consequences.
Objectives
- Students will identify the two possible referents of an ambiguous pronoun in a technical sentence.
- Students will name the subject a dangling modifier attaches to and the one the writer intended.
- Students will revise sentences so that only one reading remains available.
Vocabulary
Key words: referent, antecedent, modifier, dangling modifier, membrane, vessel
Teacher overview
A startup memo is read quickly, often at night, by an operator who acts on it immediately, so a sentence that allows two readings can send that operator to the wrong valve. This worksheet uses a fictional memo written by a project engineer to the operators who will run a new membrane treatment train, and every faulty sentence in it has a plausible second reading. The misconception this worksheet addresses is the belief that a reader can always tell what a writer meant from context. Two of the sentences here are ambiguous precisely because both readings make sense in context, which is why the reader cannot repair them and the writer has to.
Student Worksheet
The Pelbrook Water Treatment Plant and the memo below are fictional and were written for this worksheet.
Background. A membrane treatment train pushes water at high pressure through membranes held inside long tubes called vessels. Salts and other dissolved material stay behind and leave as a waste stream. Membranes are cleaned on a schedule by circulating a cleaning solution through the vessels, then rinsing them.
Memo from the project engineer to shift operators, on starting up the new train.
- (a) After the membranes are rinsed, the operators should record the pressure on both sides of the vessel before they are put back in service.
- (b) Running at full flow, the technician should watch the second stage for a pressure drop.
- (c) Do not restart the feed pump until the cleaning solution has drained from the vessel and the flush water runs clear, which takes about two hours.
- (d) The contractor told the shift lead that his crew would return on Thursday.
- (e) This is the main reason the startup slipped a week.
- (f) Only log the reading after the pump reaches steady speed.
- (g) The vessel must be isolated and the valves tagged before cleaning begins or the operator may be exposed to the solution.
- (h) We replaced the damaged seal on the second stage that was leaking.
Answer every item in complete sentences.
- Sentence (a) contains an ambiguous pronoun. Name the two things "they" could refer to, and say which reading would be dangerous on a night shift.
- Rewrite sentence (a) so that only one reading is possible.
- Sentence (b) opens with a modifier attached to the wrong subject. State what the sentence says is running at full flow, and state what the writer meant.
- Rewrite sentence (b) so the opening modifier attaches to the right subject.
- In sentence (c), the word "which" could point to two different things. Name both.
- Rewrite sentence (c) so that a new operator knows exactly what takes about two hours.
- Sentence (d) uses "his." Name the two people it could refer to, and explain why a memo cannot leave that open.
- Rewrite sentence (d) so that no pronoun is needed.
- Sentence (e) opens with "This." Explain what a reader has to do to understand that opening, then rewrite it so the reader does not have to do it.
- Sentence (f) places "only" before "log." State what the sentence says as written, state what it probably means, then rewrite it.
- Sentence (h) leaves a modifier loose. Give both readings, then rewrite the sentence to keep the reading the writer most likely intended.
- Choose the sentence in this memo whose ambiguity could cause the most harm on a night shift. Name the letter, and explain in two or three sentences what could go wrong.
From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.
Answer Key
- Answer: "They" could refer to the operators or to the membranes. The operators reading is the dangerous one, because it ties the pressure reading to the operators returning to duty rather than to the membranes, so a tired reader may return the membranes to service before recording the pressure.
- Answer: Accept any rewrite with one reading, such as: "After the membranes are rinsed, operators should record the pressure on both sides of the vessel before the membranes are put back in service." The repair replaces the pronoun with the noun.
- Answer: As written, the technician is running at full flow. The writer meant that the train, or the new treatment train, is running at full flow.
- Answer: Accept any rewrite that attaches the modifier correctly, such as: "While the train is running at full flow, the technician should watch the second stage for a pressure drop."
- Answer: "Which" could point to the flush (the time until the flush water runs clear), to the draining of the cleaning solution, or to the whole wait, draining and flushing together. Accept any two of these stated clearly.
- Answer: Accept any rewrite that assigns the two hours to one thing, such as: "Do not restart the feed pump until the cleaning solution has drained and the flush water runs clear. Draining and flushing together take about two hours."
- Answer: "His" could refer to the contractor or to the shift lead. A memo cannot leave it open because the two readings assign the Thursday work to different companies, and each one would then expect the other to show up.
- Answer: Accept any rewrite without a pronoun, such as: "The contractor told the shift lead that the contractor's crew would return on Thursday." A cleaner version reads: "The contractor's crew will return on Thursday, according to the contractor."
- Answer: The reader has to look back to sentence (d) and guess which idea "This" names, because the sentence supplies no noun of its own. Accept any rewrite that names the idea outright, such as: "The contractor's crew not returning until Thursday is the main reason the startup slipped a week."
- Answer: As written, the sentence says that logging is the only action to take after the pump reaches steady speed. It probably means that the reading should be logged only after the pump reaches steady speed. Accept a rewrite such as: "Log the reading only after the pump reaches steady speed."
- Answer: The two readings are that the seal was leaking, or that the second stage was leaking. The writer most likely meant the seal, so accept a rewrite such as: "We replaced the leaking seal on the second stage." Credit the other reading if the student rewrites it clearly and says which one they chose.
- Answer: Accept any defended choice. A strong answer names sentence (g), because the missing comma lets a reader take the exposure warning as an alternative to isolating the vessel rather than as the consequence of skipping it. Answers naming (a) or (c) earn full credit when the explanation shows a specific action an operator could take at the wrong time.
Differentiation
Support
Give these students the memo with the ambiguous word circled in each sentence, so the work begins at naming the two readings. Provide both readings for items 1 and 5 and ask students only to say which is dangerous. Allow rewrites to be completed by choosing between two supplied versions before students write their own.
Extension
Ask these students to rewrite the entire memo as a numbered procedure, then to write a paragraph on which ambiguities disappeared because of the numbering and which ones survived it. They may also add the one sentence the memo is missing, which tells the operator whom to call when the flush water does not run clear.
ELL supports
Pre-teach referent, modifier, and vessel with one labeled drawing of a membrane vessel showing the feed side, the membranes, and the waste stream. Provide a two-column chart pairing each faulty sentence with a corrected model of the same pattern. Allow students to point to the noun a pronoun should attach to before writing any explanation.
Extensions
Ask students to trade rewritten memos and read a partner's version aloud while the partner listens for any sentence that still allows two readings. A short discussion of what the listener caught, and what the writer had stopped seeing, shows why technical writers read procedures aloud before they are posted.