Educerie · SAT · Reading and Writing
Information and Ideas · II.4 Inferences
What you must be able to do
| You must be able to | What it looks like on the test |
|---|---|
| Follow a mechanism the passage sets out | Which choice most logically completes the text? |
| Extend the passage's logic by exactly one step | Not two steps, and not zero |
| Reject conclusions that need outside facts | The commonest wrong option |
| Respect qualifiers and direction | some, only, rarely, more likely |
1The idea in one paragraph
An inference question hands you a mechanism, a contrast or a condition and stops. The correct completion is the one the passage has already made inevitable — you should be able to point at the sentences that force it. If your answer needs one fact the passage did not give you, it is the wrong answer, however reasonable that fact is.
Cover the options and finish the passage yourself, in your own words. Then find the option that says what you said. This single habit is worth more on inferences than on any other skill.
2Find the logical shape first
Most inference passages are built on one of four shapes. Naming the shape tells you what the ending must do.
| Shape | Signals | The ending must |
|---|---|---|
| Mechanism | because, causes, leads to, results in | State what the mechanism produces |
| Contrast | unlike, whereas, however, by contrast | Complete the other side of the contrast |
| Condition | if, when, unless, only where | Say what follows when the condition fails or holds |
| Problem and constraint | cannot, limited by, requires | State the consequence of the constraint |
A passage that spends three sentences building a contrast does not end with a cause. Read for the shape and two options usually fall away before you have thought about their content.
3One step, not two
The right answer is the next thing that follows. Wrong options frequently follow from the right answer rather than from the passage — a second step, which the text does not license.
Seeds lose viability with time in storage; curators regrow samples to refresh them. A collection never regrown will eventually ______
One step: hold seed that no longer germinates. Two steps: lose the varieties it was created to protect. The second is probably true in the world, and it needs the first plus an extra assumption. On this test, one step wins.
4Qualifiers and direction
Check three things in your candidate against the passage: how much (all versus some), how certain (will versus may), and which way (increase or decrease).
A passage that says a factor "contributes to" an effect does not support an ending that says it "determines" it. Overstatement is the easiest wrong answer to build and the hardest to notice, because a strong sentence reads like a confident one.
5The outside-knowledge trap
These passages are often about science or history you may know something about. The test uses that: an option will state a true fact about the world that the passage never supplies. Every time you like an option, ask which sentence gives me this? If the answer is "nothing here, but I know it", eliminate it.
6What "most logically" is doing in the stem
It is a warning that several options will be logical in isolation. The comparison is not between sensible and silly; it is between an ending this passage forces and endings some other passage would force. Point at the sentences. They are the tiebreak.
Where points are lost
- Finishing the passage from general knowledge instead of from its sentences.
- Taking two steps and landing on a consequence of the answer.
- Overstating — determines where the passage said contributes to.
- Reversing direction on a contrast passage.
- Ignoring a condition — only in dry years narrows what can be concluded.
- Reading past the last full stop. The final sentence before the blank usually carries the decisive word.
- Not writing your own ending first. Eight seconds, and it immunises you against three good-looking options.
Read it right
- Read the whole passage, including the fragment before the blank.
- Name the shape: mechanism, contrast, condition, or constraint.
- Finish the sentence in your own words.
- Match, then check the qualifiers and the direction.
- Point at the sentence that forces your answer. If you cannot, start again.
Try it
Q1. Lichens absorb water and minerals directly from the air rather than from soil, which is why they colonise bare rock so successfully. It also means that whatever is suspended in the air is taken in with it, and lichens have no mechanism for excreting what they absorb. Researchers sampling lichens near a smelter therefore expect that the tissue of those lichens will ______
Which choice most logically completes the text?
A) show metal concentrations far above those of lichens sampled well away from the smelter. B) regenerate more quickly than the tissue of lichens growing on soil. C) contain fewer minerals than the surrounding rock. D) prove that the smelter is exceeding its permitted emissions.
Q2. The Ottoman postal service priced letters by distance until 1863, when it adopted a single national rate. Volumes on the longest routes rose sharply in the following decade, while volumes on the shortest routes, which had been the cheapest under the old system, ______
Which choice most logically completes the text?
A) rose more sharply still. B) grew at a slower rate or fell. C) were unaffected by the change. D) had always been the smallest part of the service.
Q3. A fungus that infects wheat can only spread when leaves stay wet for more than nine hours. Fields sown at wide spacing dry faster after rain than densely sown fields, other things being equal. A grower who sows densely in a region of long overnight dews is therefore ______
Which choice most logically completes the text?
A) likely to see more infection than a grower sowing at wide spacing in the same region. B) certain to lose the crop to the fungus. C) unlikely to see infection unless the fungus is already present in the soil. D) better protected against the fungus than a grower in a drier region.
In one breath
The ending is already decided by the passage: find the shape — mechanism, contrast, condition or constraint — finish the sentence in your own words, and then match. Take exactly one step, never two, and check the qualifiers, because an option that overstates contributes to into determines is wrong however true it sounds. If you cannot point at the sentence that forces your answer, you have brought the fact from outside and the test built that option for you.
Answers
Q1. A. absorption from air, no excretion, near a smelter — the mechanism forces accumulation Point at all three sentences. B invents regeneration, which the passage never mentions. C reverses the mechanism. D takes a second step into a legal conclusion the passage cannot support — high concentrations are not proof of exceeding a permit.
Q2. B. a flat rate makes long routes cheaper and short routes relatively dearer The contrast is set up by "while", and the short routes lost the advantage they had. A ignores the contrast the sentence is building. C contradicts it. D is a fact about size, not about what happened after 1863, and the passage gives no basis for it.
Q3. A. the condition is wetness duration; dense sowing keeps leaves wet longer One step, correctly qualified — likely, and compared with the wide-spacing grower in the same region. B overstates a probability into a certainty. C adds a soil-borne route the passage never mentions. D reverses the comparison: long dews are the risky condition, not the safe one.
Educerie · written from the published College Board* Assessment Framework for the Digital SAT Suite *(Information and Ideas, skill/knowledge testing point "Inferences"). All passages, options and explanations are original Educerie text. Last reviewed 12 September 2026.
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