Rhetorical synthesis comparisons: similarity and difference goals

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Difficulty: Intermediate
Estimated time: 25 minutes
Practice: Rhetorical Synthesis question bank

What you’ll learn

Spot a comparison goal: a similarity, a difference, “contrast” or “compare.”
Name its shape: both subjects, the trait the goal names, and the relation it wants.
Cross out a true contrast of a trait the goal doesn't name.
Tell a difference from a similarity by what the sentence says, not by “while” or “both” alone.
Check the notes for swapped subjects: which one has which detail.

Prerequisites

Rhetorical synthesis: how to answer SAT student notes questions0%
Read the goal first, name the shape, then check the notes.

Why this matters on the SAT

Two subjects, one trait, the right relation

A comparison goal names two subjects and asks for what sets them apart or what they share. Comparisons are among the most common goals in student notes questions. Every choice is usually true to the notes, and most name both subjects, so the question really asks: does this sentence compare the right things, in the right way?

SAT example

While researching ancient writings, a student has taken the following notes:

Mesopotamian scribes pressed cuneiform signs into damp clay tablets.
Some clay tablets were initially only sun-dried, but fires that destroyed buildings baked the tablets and made them more durable.
Egyptian scribes often wrote with ink on papyrus, a material vulnerable to moisture.
Papyrus documents have survived for millennia at exceptionally dry sites in Egypt.

The student wants to emphasize a contrast between how Mesopotamian clay tablets and Egyptian papyrus documents survived. Which choice most effectively uses relevant information from the notes to accomplish this goal?

A
Ancient records survived for millennia because Mesopotamian and Egyptian scribes chose materials suited to their local climates.
B
Fires sometimes made Mesopotamian clay tablets more durable, whereas exceptionally dry conditions protected Egyptian papyrus from moisture.
C
Mesopotamian scribes pressed signs into damp clay, whereas Egyptian scribes applied ink to sheets of papyrus.
D
Clay tablets and papyrus documents have both survived, showing that the writing material had little effect on preservation.

Solution to the example

Goal: a contrast between how the tablets and the papyrus survived.

Shape: both materials, how each one survived, and a difference.

Cross out: A and D say the two survived in the same way, and claim more than the notes do. C contrasts how the scribes wrote.

Check: B says fires baked the tablets and dry sites protected the papyrus. Both match the notes, so the answer is B.

C tempts most: it names both materials and says “whereas”, but how they were written isn't how they survived.

Both subjects: the two the goal names

Every student notes question runs the routine from Rhetorical synthesis: how to answer SAT student notes questions:

Read the goal first: the sentence after “The student wants to”, before the notes.
Name the answer's shape: what the right sentence must say.
Cross out what misses the goal, even when it's true to the notes.
Check the notes: every fact in the choices left matches the notes, and nothing goes beyond them.

This lesson is about step 2 when the goal asks for a comparison: emphasize a difference, emphasize a similarity, contrast or compare. Then the shape has three parts: both subjects the goal names, the attribute (the trait being compared), and the relation (a difference or a similarity). A choice that misses any one of them misses the goal, even when every word is true.

The examples in this lesson come from one set of notes about ferries:

The north ferry crosses the bay in 20 minutes.
It leaves every hour.
The south ferry crosses the bay in 45 minutes.
It leaves every 15 minutes.
A water taxi crosses the bay in 10 minutes.
Both ferries carry bikes.

In the goals, the key words are bold; in the sentences, what meets them is underlined. Here the goal is to emphasize a difference in how long the two ferries take to cross.

Correct: Both ferries: The north ferry crosses the bay in 20 minutes, while the south ferry takes 45.
Wrong: One subject: The north ferry crosses the bay in just 20 minutes.
Wrong: The wrong pair: The water taxi crosses the bay in 10 minutes, while the north ferry takes 20.

The right sentence names the two subjects the goal names and says something about each. The second sentence is about the north ferry alone. The third compares two things, but one of them is the water taxi, which the goal never mentions. Notes sometimes hold a third subject for exactly this trap. A sentence about one subject, however detailed, can't compare two.

In this question, name the two subjects from the goal before you read the choices.

Two editions of Frankenstein

Practice problem

While researching a topic, a student has taken the following notes:

Mary Shelley's novel Frankenstein was first published anonymously in three volumes in 1818.
An 1823 edition was the first to identify Shelley as the novel's author.
An 1831 edition credited Shelley and presented a substantially revised version of the text.
The 1831 edition also included an introduction in which Shelley discussed the novel's origin.

The student wants to contrast the 1818 and 1831 editions of Frankenstein. Which choice most effectively uses relevant information from the notes to accomplish this goal?

The attribute: the trait the goal names

The attribute is the trait the goal compares, such as how long the ferries take. Two subjects can differ in many ways, and the notes usually give you several of them. So find the trait in the goal, often the words after “a difference in” or “how”, and mark it before you read the choices.

Same notes, same goal: a difference in how long the two ferries take to cross.

Correct: Crossing time: The north ferry crosses the bay in 20 minutes, while the south ferry takes 45.
Wrong: How often they leave: The north ferry leaves every hour, while the south ferry leaves every 15 minutes.
Wrong: Only “they differ”: The two ferries take different amounts of time to cross the bay.

A choice can name both subjects, say “while” and still compare the wrong trait. The last sentence names the right trait but only says the ferries differ in it, not how long each one takes. The right sentence gives the detail for each subject.

Check your understanding:

The goal is to emphasize a difference in how often the two ferries leave. Which fits? The north ferry crosses in 20 minutes, while the south ferry takes 45. or The north ferry leaves every hour, while the south ferry leaves every 15 minutes.

In this question, mark the trait in the goal before you read the choices.

Two migrations

Practice problem

While researching a topic, a student has taken the following notes:

Monarch butterflies migrate each fall from Canada and the northern United States to oyamel fir forests in central Mexico.
Painted Lady butterflies migrate each spring from North Africa to southern and central Europe.
Both butterfly species travel thousands of miles during migration.
Monarch butterflies navigate using an internal compass that senses the sun’s position.
Painted Lady butterflies take advantage of favorable wind patterns during migration.

The student wants to emphasize how the directions of the two species’ migration routes differ. Which choice most effectively uses relevant information from the notes to accomplish this goal?

The relation: a difference or a similarity

The relation is what the goal wants said about the trait: that the two subjects differ in it, or that they share it. “Emphasize a difference” and “contrast” want a difference; “emphasize a similarity”, “shared” and “in common” want something true of both. “Compare” in a goal (not the transition job) usually wants how the two differ in the trait the goal names.

Comparison words show which relation a sentence states:

Relation	Usual words	The sentence says
Difference	“while”, “whereas”, “unlike”, “by contrast”, “but”, “however”	the trait isn't the same for the two
Similarity	“both”, “like”, “similarly”, “also”, “share”, “in common”	the trait is the same for both

The wrong relation is the trap comparison questions set most often: a choice names both subjects and the right trait, but says they differ when the goal wants what they share, or the reverse. These words make a fast first pass: when the goal wants a similarity, cross out the choices that set the subjects apart with “whereas” or “while”. Here the goal is to emphasize a similarity between the two ferries.

Correct: Shared trait: Both ferries carry bikes.
Correct: A difference granted: Although the ferries take different times to cross, both carry bikes.
Wrong: A difference: The north ferry crosses in 20 minutes, while the south ferry takes 45.
Wrong: A false difference: Unlike the north ferry, the south ferry carries bikes.

The second sentence opens with “although”, which usually signals a contrast, yet it states a similarity: the “although” clause only grants a difference (a “while” clause can do the same), and the rest of the sentence says what both ferries share. The last sentence frames a shared trait as a difference, and the notes say both ferries carry bikes, so it's false as well. A difference can also come with no comparison word at all: The north ferry crosses in 20 minutes; the south ferry takes 45. Judge the relation by what the sentence says about each subject, not by its first word or its frame.

Check your understanding:

The goal is to emphasize a similarity between the two ferries. Does this fit? While the north ferry is faster, both ferries carry bikes.

In this question, sort the choices by the relation each one states.

Two seed banks

Practice problem

While researching efforts to protect plant species, a student has taken the following notes:

The Svalbard Global Seed Vault opened in Norway in 2008.
The vault stores backup samples of seeds from food crops.
Its location inside an Arctic mountain helps keep the seeds cold.
The Millennium Seed Bank opened at Wakehurst in England in 2000.
The bank stores seeds from wild plant species around the world.
Both projects preserve plant diversity for future generations.

The student wants to explain a purpose shared by the two projects. Which choice most effectively uses relevant information from the notes to accomplish this goal?

Check the notes: which subject has which detail

A comparison puts two subjects and a detail for each in one sentence, so the swap from the previous lesson takes its sharpest form here: the two subjects trade details. When two choices have the same shape, match each detail to its subject in the notes. The goal again: a difference in how long the two ferries take to cross.

Correct: Matches the notes: The north ferry crosses the bay in 20 minutes, while the south ferry takes 45.
Wrong: Swapped: The north ferry takes 45 minutes to cross the bay, while the south ferry takes 20.

The swapped sentence has both ferries, the right trait, a difference and the right numbers. Only the notes catch it. A sentence that opens with “both” can fail the same way, by giving one subject's detail to the other: Both ferries leave every 15 minutes is false, because the north ferry leaves every hour. When two choices look alike, check who does what.

In this question, let the notes decide between two choices with the same shape.

Two kinds of bee nest

Practice problem

While researching a topic, a student has taken the following notes:

Leafcutter bees and mining bees are solitary bees.
Female leafcutter bees build nests in existing cavities, such as hollow stems.
Leafcutter bees line their nests with pieces cut from leaves.
Female mining bees dig underground tunnels for their nests.
Mining bees typically build their nests in areas of exposed soil.

The student wants to compare how leafcutter bees and mining bees build their nests. Which choice most effectively uses relevant information from the notes to accomplish this goal?

Example: each one's part in the same event

In this question, every choice names both women, and one true fact is the wrong kind of fact.

Worked example

While researching a topic, a student has taken the following notes:

On December 1, 1955, Rosa Parks was arrested in Montgomery, Alabama, for refusing to give up her bus seat.
Jo Ann Robinson, an English professor at Alabama State College, was a leader in the Women’s Political Council (WPC).
After Parks’s arrest, Robinson and her students produced tens of thousands of flyers calling for a one-day bus boycott on December 5.
The boycott lasted 381 days and helped bring national attention to segregated public transportation in Montgomery.
Parks became a widely recognized symbol of the boycott, while Robinson did much of the early organizing work but avoided the spotlight because she feared losing her job.

The student wants to compare how Parks and Robinson each contributed to launching the Montgomery Bus Boycott. Which choice most effectively uses relevant information from the notes to accomplish this goal?

A
Parks’s arrest sparked the boycott and made her a powerful symbol, while Robinson avoided the spotlight because she feared losing her job as the boycott brought national attention to segregated transportation in Montgomery.
B
After Parks’s arrest, Robinson and her students produced tens of thousands of flyers calling for a one-day boycott on December 5, and Robinson became the widely recognized symbol of the boycott.
C
Parks’s arrest sparked the boycott and made her a powerful symbol, while Robinson, working through the WPC, organized the flyer campaign that called for the initial December 5 boycott.
D
Parks’s arrest sparked the boycott and led to a 381-day protest, while Robinson, working through the WPC, produced flyers calling for a 381-day boycott beginning on December 5.

Step 1

Read the goal first

The goal is to compare how Parks and Robinson each contributed to launching the Montgomery Bus Boycott. Both subjects: Parks and Robinson. The attribute: what each one did to get the boycott started. “Compare how each contributed” wants each woman's part, set against the other's.

Step 2

Name the shape

The notes give each woman's part. Parks: she was arrested in Montgomery, Alabama, for refusing to give up her bus seat, and she became the boycott's symbol. Robinson: she and her students produced tens of thousands of flyers calling for the one-day boycott on December 5. So the shape is Parks's arrest and Robinson's flyers, side by side.

Step 3

Cross out what misses the goal

A tempts most: it has both women and a “while”, and every fact in it is true. But Robinson's half says why she avoided the spotlight, and that isn't a part she played in launching the boycott. A compares the wrong trait, so it goes.

Step 4

Check the notes

B, C and D all give each woman a part, so the notes decide. B makes Robinson the boycott's symbol, but the notes say Parks became a widely recognized symbol of the boycott; Robinson stayed out of the spotlight. D says the flyers called for a 381-day boycott, but they called for one day; it was the boycott that lasted 381 days. B and D go.

Step 5

Check the last choice

C gives Parks the arrest that sparked the boycott and the role of its symbol, and gives Robinson the flyer campaign for the first day, through the Women's Political Council. Each part sits on the right woman. The answer is C.

Example: every choice says “both”

In this question, all four choices state a similarity, so the comparison words can't decide.

Worked example

While researching a topic, a student has taken the following notes:

The Milky Way is a disk-shaped galaxy that contains interstellar dust.
This dust absorbs and scatters visible light, making it difficult to observe the galaxy’s far side with optical telescopes.
Infrared surveys can detect many stars through dust more effectively than visible-light observations can.
Radio telescopes can detect 21-centimeter emission from neutral hydrogen gas, and these radio waves pass through dust.
Astronomers often combine infrared and radio data to build a more complete map of the Milky Way’s structure.

The student wants to emphasize a similarity between infrared surveys and radio observations as tools for mapping the Milky Way. Which choice most effectively uses relevant information from the notes to accomplish this goal?

A
Both infrared surveys and radio observations can penetrate interstellar dust, allowing astronomers to detect many stars on the Milky Way’s far side that optical telescopes miss.
B
Both infrared surveys and radio observations use wavelengths that pass through interstellar dust, helping astronomers map regions hidden from visible-light telescopes.
C
Both infrared surveys and radio observations can pass through interstellar dust, so either method by itself can produce a complete map of the Milky Way’s structure.
D
Both infrared surveys and radio observations focus on interstellar dust itself, and astronomers use their measurements of that dust to map the Milky Way.

Step 1

Read the goal first

The goal is to emphasize a similarity between infrared surveys and radio observations as tools for mapping the Milky Way. Both subjects: infrared and radio. The attribute: what makes each useful for mapping. The relation: something they share.

Step 2

Name the shape

Every choice opens with “Both infrared surveys and radio observations” and says something about mapping, so nothing can be crossed out yet. The notes decide, one claim at a time.

Step 3

Check who does what

A tempts most, because infrared really can detect many stars: Infrared surveys can detect many stars through dust. But radio picks up something else: Radio telescopes can detect 21-centimeter emission from neutral hydrogen gas. A gives what only infrared does to both, so it goes.

Step 4

Check the other claims

C says either tool alone can make a complete map, but the notes say Astronomers often combine infrared and radio data to get a more complete one. D says both study the dust itself, when the notes say both see through it. C and D go.

Step 5

Check the last choice

B: both use wavelengths that pass through dust, which helps map what visible-light telescopes can't see. Infrared sees stars through dust, and radio waves pass through it, so the shared trait is true of each. The answer is B.

Practice problems

These questions mix the checks, so on each one, read the goal first and name all three parts of the shape before you read the choices.

Two novels of one day

Practice problem

While researching literary narrative techniques, a student has taken the following notes:

Virginia Woolf’s Mrs Dalloway follows Clarissa Dalloway and other Londoners over the course of one day.
As Clarissa runs errands and prepares for a party, the narration frequently moves into characters’ memories and thoughts.
James Joyce’s Ulysses follows Leopold Bloom, Stephen Dedalus, and other Dubliners over the course of one day.
As the characters walk, eat, and work, the narration frequently moves into their thoughts and associations.

The student wants to explain a similarity in how the two novels connect characters’ inner lives with ordinary experiences in a city. Which choice most effectively uses relevant information from the notes to accomplish this goal?

Hearings and participatory budgeting

Practice problem

While researching civic participation, a student has taken the following notes:

Harbor City’s charter requires the city council to hold a public hearing before approving the annual budget.
At the hearing, residents may recommend how public funds should be spent.
Council members retain final authority and are not required to follow residents’ recommendations.
Harbor City later established a participatory budgeting pilot for a designated portion of public funds.
Through the pilot, residents propose neighborhood projects and vote on eligible proposals.
The city commits to funding the eligible projects that receive the most votes.

The student wants to explain a difference in the decision-making authority residents have under the two methods of civic participation. Which choice most effectively uses relevant information from the notes to accomplish this goal?

Weather stations and satellites

Practice problem

While researching a topic, a student has taken the following notes:

Scientists estimate global surface temperature change using both ground-based weather stations and satellite instruments.
Weather stations measure air temperature directly at specific locations.
Weather stations are unevenly distributed, with many more stations on land than over the oceans.
Temperature readings from weather stations can be influenced by very local changes, such as new buildings or pavement near the station.
Satellites can collect data across most of Earth, including remote regions and oceans.
Satellites do not measure surface air temperature directly; their readings must be calibrated to estimate temperature.
Modern satellite temperature records are relatively short compared with many weather-station records.

The student wants to compare some limitations of weather-station data and satellite data for tracking global temperature change. Which choice most effectively uses relevant information from the notes to accomplish this goal?

Two executive branches

Practice problem

While researching a topic, a student has taken the following notes:

In Switzerland, the federal executive branch is led by the Federal Council, a group of seven members.
The Federal Council is elected by the Federal Assembly (Switzerland’s national legislature) for four-year terms.
The Federal Council makes major decisions collectively, rather than having a single leader direct the executive branch.
Each year, one Federal Council member serves as president, but the presidency rotates annually among the seven members.
In the United States, the executive branch is led by a single president who serves as head of the executive branch.
The US president is chosen through the Electoral College for a four-year term.

The student wants to emphasize how executive power is distributed differently in Switzerland and the United States. Which choice most effectively uses information from the notes to accomplish this goal?

Finish the lesson

8 practice examples left

Finish the remaining questions correctly to complete this lesson.

Quick recap

Both subjects: the right sentence names the two subjects the goal names and says something about each.
The attribute: it compares the trait the goal names and gives the detail for each; a true contrast of another trait is a common trap.
The relation: a difference for a difference, a similarity for a similarity; the wrong relation is the trap you'll meet most. Judge it by what the sentence says about each subject, not by “while” or “both”.
Check the notes: when two choices share a shape, match each detail to its subject.
Every notes question: read the goal first, name the answer's shape (for a comparison, both subjects, the attribute and the relation), cross out what misses the goal, then check the notes.

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List every demand the goal makes and give the audience what it needs.

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