The Shade Audit
A city council packet includes this memo, and a student is annotating it for a summary assignment.
When Riverton planted 400 silver maples along Third Street in 2009, the goal was shade. By 2021 the trees had grown fast-silver maples can add two feet a year-and August sidewalk temperatures had dropped by nine degrees. But roots had also lifted 62 percent of the sidewalk panels within ten feet of each trunk, and the city had paid $340,000 in trip-and-fall settlements. Riverton's arborist now recommends a slower-growing species that will take twice as long to produce the same canopy. 'Shade you can wait for,' she told the council. 'A broken hip you can't.'
1. A classmate drafts this summary: 'Riverton should cut down its silver maples because they cost too much.' Identify what is wrong with that summary and write a better one-sentence version.
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The draft fails on two counts. First, it converts a recommendation about future planting into a removal order; the memo never says what to do with the existing 400 trees, only that the arborist recommends a different species going forward. Second, it elevates one supporting figure ($340,000) to the status of main idea.
A defensible summary states the tradeoff and the recommendation:
Riverton got fast shade from silver maples but paid for it in damaged sidewalks and injury settlements, so its arborist now favors a slower species that trades quick canopy for durability.
Test any summary by asking: does it survive if I delete one number? The good version does; the draft collapses without its dollar figure.
2. Is the inference 'the arborist believes Riverton made a mistake in 2009' supported by the memo?
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Only weakly, and the wording matters. The memo establishes that the arborist now recommends a different species. It does not say she characterizes the 2009 planting as an error, and the quote ('Shade you can wait for') is forward-looking advice to the council, not a verdict on the past.
A reader can reasonably infer she regards the original species choice as a poor long-term fit, since she proposes replacing it on the same street. But inferring that she blames the 2009 decision-makers adds a judgment the text does not supply-the memo gives no information about what was known in 2009 about silver maple roots.
The discipline here: an inference must be licensed by specific words. 'Now recommends' licenses a change of view. It does not license assigning fault.
3. Which detail in the memo is most load-bearing for the central idea, and which is most replaceable?
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Rank details by what they would do to the argument if removed.
- Most load-bearing: the 62 percent of lifted panels. This establishes that the damage is widespread rather than an isolated nuisance. Remove it and the memo becomes a story about a few bad sidewalks, which would not justify changing species citywide.
- Also doing work: 'can add two feet a year.' This explains why the trees were attractive in the first place-it is the benefit side of the tradeoff. Without it, the arborist's position looks like a preference rather than a calculation.
- Most replaceable: the exact $340,000 figure. The point is that settlements have been substantial and recurring. 'Six figures in settlements' would carry the same weight; the precise number adds vividness, not reasoning.
Judging relevance means asking what job a detail performs, not how interesting it is.