Science Passages: Reading & Science Tips

🔬 ACT Reading + Science Tips

Part 1 of 7 — ACT Reading Overview: Natural-Science Passages

The Enhanced ACT Reading test gives you 36 questions in 40 minutes (about 67 seconds per question), and every question has four answer choices. The questions come in four passage sets, usually nine questions each, drawn from four families: literary narrative, social science, humanities, and natural science. One set may be a pair of shorter passages on a shared topic.

This lesson focuses on the natural-science set, because it is the one that feels most like a textbook. It might explain how a natural process works, tell the story of a discovery, describe a study and its results, or weigh two explanations for a puzzling observation. You do not need outside science knowledge. Every answer is in the passage; the challenge is reading dense prose accurately.

Map the Passage by Paragraph Role

Science passages are built from a small set of paragraph jobs. As you read, label each paragraph in two or three words:

1. Phenomenon: the thing being explained (a bird that survives freezing nights).
2. Question or puzzle: what scientists did not understand.
3. Method: what researchers did, measured, or compared.
4. Result: what they found, often with numbers.
5. Interpretation: what the result means, usually hedged.
6. Open questions: what is still unknown, or a caveat.

A map like "P1 puzzle, P2 method, P3 result, P4 caveat" answers most main-idea and function questions without rereading.

Technical Terms: Read the Definition the Passage Gives You

The ACT never expects you to know jargon. When a term appears, the passage defines it nearby. Look for these signals:

• Appositives: "torpor, a deep, temporary drop in body temperature and activity, ..."
• Naming phrases: "known as," "called," "referred to as," "that is"
• Examples: "keystone species, such as sea otters, ..."
• Contrast: "Unlike annual plants, which die after one season, perennials ..."

If a sentence is thick with terms, give each one a short label (the "X-protein," the "deep roots") and keep reading. Only stop to decode a term when a question asks about it.

Cause and Effect: Follow the Chain

Many natural-science questions ask why something happens or what results from it. Underline or note the links: because, so, as a result, therefore, leads to, triggers, allows, prevents, depends on. Science prose often builds a chain (A causes B, which causes C). A common wrong answer skips a link or reverses the direction, saying C causes A.

Hedges and Limits: Claims Mean Exactly What They Say

Scientists write carefully, and ACT answers reward matching their caution.

Author's Attitude Toward a Finding

Questions ask how the author regards a study, a theory, or a scientist. Look at word choice: striking, elegant, compelling signal approval; intriguing but limited, premature, unproven signal caution; flawed, overstated signal criticism. Science authors are rarely extreme, so "cautiously optimistic," "interested but skeptical," and "measured approval" are common correct answers, while "dismissive" or "unreservedly enthusiastic" usually overstate the tone.

Worked Examples

Read this short natural-science passage, then open each example.

On cold nights, many hummingbirds face a serious problem. Their tiny bodies lose heat quickly, and staying warm requires burning energy at a rate their stored fat cannot support until morning. Many species solve this with torpor, a temporary state in which body temperature and heart rate fall far below their daytime levels. A bird in deep torpor can let its body temperature drop by more than 20 °C, which sharply reduces the energy it spends overnight. The cost is vulnerability: a torpid bird responds slowly and needs time to warm up again at dawn. Researchers studying birds in mountain habitats have reported that individuals entering torpor more often tended to carry less fat in the evening, which suggests the state may be used most when energy reserves are low.

Question: As it is used in the passage, torpor most nearly means:

• a permanent slowing of growth in young birds
• a temporary drop in body temperature and activity
• a period of rapid feeding before nightfall
• a long seasonal migration to warmer areas

Solution:

1. Find the definition the passage supplies: torpor is "a temporary state in which body temperature and heart rate fall far below their daytime levels."
2. Match the key words: temporary and lower body temperature.
3. The answer is a temporary drop in body temperature and activity. "Permanent" contradicts "temporary," and feeding and migration are never mentioned.

Question: According to the passage, the researchers' observation about fat reserves suggests that hummingbirds:

• enter torpor every night regardless of their condition
• gain fat as a direct result of entering torpor
• may rely on torpor most when stored energy is low
• avoid torpor because it leaves them vulnerable

Solution:

1. The observation: birds that entered torpor more often "tended to carry less fat in the evening."
2. The passage's own interpretation is hedged: the pattern "suggests the state may be used most when energy reserves are low."
3. The answer is may rely on torpor most when stored energy is low. "Every night regardless" ignores the link to fat. "Gain fat as a result" reverses the direction: low fat comes first, torpor follows. The vulnerability is a cost the passage mentions, but it does not say birds avoid torpor.

Practice Passage A: How Ants Plant Forests 🎯

Walk through an eastern North American forest in spring and you may see wildflowers whose seeds carry a small, pale, fatty attachment. This structure, called an elaiosome, contains no part of the embryo; it exists, as far as botanists can tell, to attract ants. A foraging ant grips the elaiosome, hauls the entire seed back to its nest, and feeds the fatty portion to its larvae. The seed itself, hard and inedible to the ants, is then discarded, often in an underground waste chamber rich in nutrients from the colony's refuse.

This arrangement, known as myrmecochory, appears to benefit the plant in several ways. Seeds moved to a nest escape the rodents that eat seeds left on the surface, and seeds buried even a few centimeters deep are better protected from ground fires. Because the waste chambers are rich in nutrients, seedlings there may also begin life in better soil than seedlings that sprout where the seed simply fell. The distances involved are short, usually only a few meters, so ants are not long-distance carriers; their contribution is less about how far seeds travel than about where they land.

What Does the Wording Allow? 🔍

ACT-Style Practice: Map Before You Answer

Spend about 90 seconds on this passage. Write a two-word label for each paragraph, then check your map.

(1) For decades, gardeners noticed that young plants growing beside certain deep-rooted trees seemed to survive dry summers better than plants growing in open ground. (2) One proposed explanation is hydraulic lift: at night, when the leaves stop releasing water, deep roots draw moisture from wet soil far below and leak some of it into the dry upper soil. (3) In a greenhouse trial, researchers placed shallow-rooted seedlings beside oak saplings whose deep roots reached a moist lower layer. Soil moisture near the surface rose overnight and fell during the day, and seedlings beside the oaks wilted less than seedlings growing alone. (4) The authors called their results preliminary. Greenhouse soil is far more uniform than a forest floor, and it remains unclear how much lifted water neighboring plants actually absorb in the wild.

A question asking for the author's attitude toward the hypothesis points you to Paragraph 4: the finding is promising but unconfirmed. A question about why moisture rose overnight points you to Paragraph 2: the leaves stop releasing water at night, so roots can redistribute it.

ACT-Style Questions on the Hydraulic-Lift Passage 📋

Key Takeaways

• Reading format: 36 questions in 40 minutes, four passage sets of about nine questions, four choices each. Natural science is one of the four families.
• No outside science needed. Every answer is supported by the passage itself.
• Map paragraphs by role: phenomenon, puzzle, method, result, interpretation, caveat.
• Terms are defined in context. Use appositives, "called," "known as," examples, and contrasts.
• Follow cause-and-effect chains and watch for answers that skip a link or reverse the direction.
• Match the passage's caution. Suggests, preliminary, under laboratory conditions, and associated with all limit what you can conclude.
• Author's attitude is usually measured. "Interested but cautious" beats "dismissive" or "fully convinced" unless the text is extreme.

📊 ACT Science Overview

Part 2 of 7 — The Science Test and Reading Tables and Graphs

On the Enhanced ACT, the Science test is optional: 40 questions in 40 minutes (60 seconds per question), four answer choices each. It is reported as its own score and feeds the STEM score, but it is not part of the composite, which averages English, Math, and Reading. Check whether the colleges on your list want it before test day.

The test is a series of passages, each followed by a set of questions. Despite the name, it is mainly a data-reasoning test. Introductory biology, chemistry, physics, and earth science ideas appear, but the answers come from the figures and text in front of you, not from memorized facts.

The Figure-First Method

Before you read any question, spend about 15 seconds on each figure:

1. Title: what was studied.
2. Axes or column headings: which variables are shown. The variable the researcher set is usually on the horizontal axis or in the left column.
3. Units: g vs mg, seconds vs minutes, °C vs K. Unit mismatches are a top trap.
4. Key or legend: what each line, symbol, or bar stands for.
5. The overall trend: as one variable goes up, does the other go up, go down, or change direction?

Then go to the questions and return to the figure only for the values each question needs.

The Four Basic Question Types

Trend Vocabulary

When two measured variables move in opposite directions over a day or a season, describe each one separately. If temperature rises then falls, an inversely related variable will fall then rise: a mirror image.

Greatest Value vs Greatest Change

These are different questions, and the ACT pairs them on purpose.

• Greatest value asks which number is biggest in a column or row.
• Greatest change asks which difference (final minus initial) is biggest.

A site can start low and grow the most while another site starts high, grows little, and still has the largest final value. Always compute the differences.

Size of a change ignores direction. If values go 18, 26, 31, 33, 32, the changes are +8, +5, +2, and −1. The smallest change is the last one (size 1), even though it is a decrease.

Units and Scale

• Convert before comparing: 1 g = 1,000 mg; 1 min = 60 s; 1 L = 1,000 mL.
• Read the scale on each axis. Two graphs side by side may use different scales.
• Do not copy a number from one column into an answer that asks about another column. If a choice shows the right digits with the wrong unit, it is a trap.

Worked Examples

Table 1 shows measurements in a lake on a summer afternoon.

Question: According to Table 1, at what depth was the dissolved oxygen 5.2 mg/L, and how did oxygen change as depth increased?

Solution:

1. Find 5.2 in the oxygen column and read left: 8 m.
2. Scan the oxygen column top to bottom: 8.6, 7.9, 5.2, 3.0, 2.7. Every value is lower than the one before.
3. Oxygen decreased at every depth, an inverse relationship with depth. Temperature also fell, so oxygen and temperature moved together (both down).
4. Trap check: a choice of "5.2 m" copies the oxygen value into the depth column.

Question: Between which two consecutive depths did the water temperature change the most?

Solution:

1. Compute each change: 24 → 21 is 3; 21 → 14 is 7; 14 → 9 is 5; 9 → 8 is 1.
2. The largest change is 7 °C, between 4 m and 8 m.
3. Notice the change shrinks to 1 °C at the bottom: temperature levels off in deep water. A question asking which depth had the lowest temperature would be a different question (16 m).

Practice: Read the Table 🎯

A student recorded how long it took ice cubes of the same size to melt in 250 mL of water at different starting temperatures.

Compute the Changes ✏️

Use this table of a moth's wing-beat rate.

1. By how many wing beats per second did the rate change from 15 °C to 35 °C? (Enter a positive number.)

2. What is the SIZE of the smallest change between consecutive temperatures? (Enter a positive number.)

3. At what air temperature (°C) was the wing-beat rate highest?

ACT-Style Practice: Value or Change?

Three stream sites were sampled for insect larvae (larvae per square meter).

Answer each in your head, then check.

ACT Tip: If one answer choice names the same site for "most" and "biggest increase," check both numbers. The test often pairs a high-but-flat site with a low-but-fast-growing one.

ACT-Style Questions: Two Variables, One Figure 📋

An environmental scientist recorded conditions at a city park on one spring day.

Key Takeaways

• Science format: optional, 40 questions in 40 minutes, four choices; reported separately and not part of the composite.
• Three passage formats: Data Representation, Research Summaries, Conflicting Viewpoints.
• Figure first: title, axes or headings, units, key, overall trend, in about 15 seconds.
• Look-up vs reverse look-up: find the value in the right column, then read across. Never copy digits into the wrong column.
• Greatest value is not greatest change. Compute differences; size of a change ignores its direction.
• Name the pattern: direct, inverse, peak, levels off. Two inversely related variables make a mirror image.
• Convert units before comparing.

🧪 Cross-Section Strategies

Part 3 of 7 — Experiments and Evidence in Both Reading and Science

Two habits earn points on both the Reading and Science tests:

1. The answer is in the passage. Every correct choice can be pointed to: a sentence, a table row, a data point. If you cannot point to it, eliminate it.
2. Understand the experiment. Reading natural-science passages describe studies in prose; Science Research Summaries describe them with tables. The logic is the same, and the questions are the same: what was changed, what was measured, what was kept the same, and what the results support.

The Three Kinds of Variables

A control group (or control trial) is a trial with the independent variable at zero or at a normal baseline, such as 0% extract or no fertilizer. Its job is to show what happens without the treatment, so any difference in the treated trials can be credited to the treatment.

Turn Prose Into a Mini-Table

When a Reading passage describes a study in sentences, sketch it as a table in your head:

Researchers grew pea plants in pots with 0, 5, or 10 grams of compost. All pots received the same light and water. After four weeks, they weighed each plant.

Now every design question is a look-up.

Isolating One Variable

To credit an outcome to one factor, compare two trials that are identical except for that factor. If two trials differ in two ways, you cannot tell which change caused the difference. This is called a confound.

• Effect of light alone: compare Trials 1 and 2 (same temperature).
• Effect of temperature alone: compare Trials 2 and 3 (same light).
• Trials 1 and 3 differ in both, so they cannot isolate either factor.

Fixing a confound: If one group differs from the others in an extra way (a shaded pot among sunny pots), the fix is to make that extra condition the same for every group, not to remove the group or add more levels.

Hypotheses: Support, Weaken, or Neither

A hypothesis makes a prediction. To judge a result, ask: "What would the hypothesis expect to see?"

A new data point that fits between existing values, or continues the trend, is consistent with the hypothesis. The result that contradicts is the one that reverses the pattern.

The Same Logic in Reading

Natural-science Reading passages ask the same questions in different words:

• "The researchers included the untreated plots in order to ..." = purpose of the control.
• "Which finding, if true, would most weaken the author's claim?" = contradicting result.
• "The study was designed to determine whether ..." = independent and dependent variables.
• "The author suggests the results are limited because ..." = confound or narrow conditions.

Worked Examples

A marine biologist suspected that a common snail avoids rock pools where crabs are present, even when it cannot see them. She filled twelve identical tanks with seawater. Six tanks received water that had previously held a crab; the other six received plain seawater. She placed ten snails in each tank and, after one hour, counted how many had climbed above the waterline.

Question: What was the purpose of the six tanks with plain seawater?

Solution:

1. Build the mini-table. Changed: water with or without crab scent. Measured: snails above the waterline. Same: tanks, snail number, time.
2. The plain-seawater tanks have no crab scent, so they are the control.
3. They show how many snails climb out without any crab signal, so a higher count in crab-scented tanks can be credited to the scent. They were not a second treatment or a way to test vision.

Question: Which two trials show the effect of cart mass alone?

Solution:

1. Mass alone means everything else must match.
2. Trials 2 and 3: height 40 cm both, surface tile both, mass 200 vs 400 g. ✅
3. The distance barely changes (180 vs 178 cm), so mass had little effect. Trials 3 and 4 isolate surface instead, and Trials 1 and 2 isolate height.

Practice: Read the Design 🎯

To test whether caffeine affects how fast a water flea's heart beats, a student placed individual water fleas in drops of pond water containing 0, 10, 20, or 40 milligrams of caffeine per liter. Every drop was kept at 21 °C and viewed under the same microscope. After two minutes in the solution, the student counted heartbeats for 15 seconds and multiplied by four.

Name the Role 🔍

A researcher tested whether soil salt level affects how many radish seeds sprout. She planted 50 seeds in each of four trays with 0, 2, 4, or 8 g of salt per kg of soil. All trays received the same water and light for 10 days, and then she counted the sprouted seeds.

ACT-Style Practice: Predict Before You Check

A student hypothesizes that brighter light makes a pond plant release more oxygen bubbles. Before looking at any result, say what the hypothesis predicts: more light, more bubbles.

A closer lamp means brighter light. Decide whether each new result would support, contradict, or fit the pattern.

ACT Tip: "Contradict" questions usually hide the right answer in a data point beyond the tested range that reverses the trend. Points that fit between rows almost never contradict.

ACT-Style Questions: Hypotheses and Results 📋

Key Takeaways

• Point to the evidence. In both Reading and Science, a correct answer is backed by a specific sentence or data point.
• Independent = what is changed on purpose; dependent = what is measured; controlled = what stays the same.
• The control group shows the result without the treatment, so differences can be credited to the treatment.
• Isolate a variable by comparing trials that differ in that one factor only. Two differences = a confound.
• Fix a confound by making the extra condition the same for every group.
• Judge a hypothesis by its prediction. A strong result in the predicted direction supports it; a reversal of the pattern contradicts it; in-between points are consistent.
• Reading uses the same logic in prose: purpose of a control, what would weaken a claim, what the study was designed to test.

🧗 Managing Difficult Passages

Part 4 of 7 — Competing Explanations, Dense Prose, and Multiple Figures

Some passages feel hard before you answer a single question. Usually the difficulty comes from one of three sources, and each has a fix.

Conflicting Viewpoints: The Four-Step Method

A Conflicting Viewpoints passage gives a short introduction (facts everyone accepts), then two or more explanations from Scientist 1, Scientist 2, Student A, Hypothesis 1, and so on. The introduction is common ground. The viewpoints are claims.

1. Read the introduction for the shared facts and the puzzle.
2. Write a one-line summary of each view in your own words: "S1: warm water, less oxygen. S2: mussels eat the food."
3. List agreement and disagreement. What do both accept? What exactly do they dispute: the cause, the timing, the mechanism?
4. Predict reactions to new evidence. For each view, ask: "If this were true, would this person be pleased or worried?"

Common Question Types

"Support A but NOT B" needs two checks. A finding that fits both views, or fits neither, is wrong. A finding that fits A and directly undercuts B's mechanism is right.

Opposite predictions cannot both be supported. When two views predict opposite outcomes for the same test, a result that supports one must weaken the other.

Reading Passages That Weigh Explanations

Natural-science Reading passages often do the same thing in essay form: "Some researchers argue X. Others point to Y. New evidence complicates both." Track three things:

• Who holds each view (named researchers, "a competing camp," "most geologists").
• The evidence each side cites. Questions ask which detail supports which side.
• The author's lean. Words like more persuasive, remains the stronger explanation, or fails to account for reveal it. If the author stays neutral, the correct answer will say so.

Dense Prose: Tactics That Save Time

• Label, don't decode. Call "phosphoenolpyruvate carboxylase" the enzyme and move on. A question will tell you if the name matters.
• Read the first and last sentence of each paragraph closely, and skim long lists of examples. Return when a question sends you there.
• Use the question to aim your rereading. A line or paragraph reference narrows the search; key nouns in the stem tell you where to look.

Linking Two Figures Through a Shared Variable

Some questions need two figures. One table connects condition A to variable X; another connects X to result Y. X is the bridge.

1. Use the first figure to find the value of the bridge variable.
2. Carry that value to the second figure.
3. If it falls between two rows, interpolate: take the value halfway (or proportionally) between the neighboring results.

Example: Table 1 says a field's soil was 17 °C at noon. Table 2 gives a beetle's activity as 26 moves per minute at 16 °C and 34 at 18 °C. At noon the activity is about 30 moves per minute, halfway between.

Worked Examples

Introduction: A small island's lizards have longer back legs today than lizards on the mainland where the population originated about 60 years ago.

Scientist 1: The island has few trees and many open rocks. Lizards with longer legs run faster on open ground and escape predators, so over generations, long-legged lizards left more offspring.

Scientist 2: The longer legs do not reflect inherited differences at all. Young lizards that grow up running on rocks simply develop longer legs, just as muscles grow with use. Offspring raised on the mainland would have normal legs.

Question: Which finding would support Scientist 2 but NOT Scientist 1?

Solution:

1. S1 says legs changed because long-legged lizards reproduced more (an inherited change). S2 says legs grow longer with use during each lizard's life.
2. A finding that fits S2 only: island lizard eggs hatched and raised on the mainland grew normal-length legs. If the trait were inherited, these lizards should keep long legs, so this undercuts S1.
3. A finding like "long-legged lizards escape predators faster" supports S1, not S2. "The island has many rocks" is in both accounts, so it supports neither over the other.

Table 1: Altitude and air temperature on a mountain trail

Table 2: Air temperature and a beetle's walking speed

Question: About how fast would the beetle walk at 1,500 m?

Solution:

1. Table 1: 1,500 m → 15 °C. Temperature is the bridge.
2. Table 2: 15 °C is halfway between 14 °C (2.6 cm/s) and 16 °C (3.2 cm/s).
3. Halfway between 2.6 and 3.2 is 2.9 cm/s. Trap: reading "15" as a speed, or using 1,500 to look up Table 2 directly.

Practice: Conflicting Viewpoints 🎯

Introduction: In a mountain valley, the trees on south-facing slopes begin dropping their leaves about two weeks earlier in autumn than the same species on north-facing slopes. South-facing slopes in this valley receive more direct sunlight.

Hypothesis 1: South-facing soils dry out faster in late summer. Water-stressed trees shed their leaves early to reduce water loss through the leaves.

Hypothesis 2: Soil moisture plays no role. The extra sunlight warms the leaves on south-facing slopes, speeding up the aging of leaf tissue, so leaves wear out and fall sooner.

ACT-Style Practice: A Reading Passage That Weighs Two Views

Read for who claims what and the author's lean. Give yourself about two minutes.

When the first fossils of feathered dinosaurs were described, many paleontologists assumed feathers had evolved for flight. That view has lost ground. Several of the feathered species were far too heavy to fly, and their feathers were short and fuzzy rather than broad and stiff. A second camp proposed that early feathers served as insulation, trapping body heat the way down does in modern chicks. Still other researchers point to fossils in which long feathers are arranged in patterns on the arms and tail, and they argue that feathers first worked as display, much as a peacock's tail does today.

The insulation and display ideas need not be rivals. A structure can begin with one job and later take on others; the earliest fuzz may have kept small dinosaurs warm, while later, larger feathers attracted mates. What seems clear is that flight came late. Feathers were not invented for the sky, but the sky eventually found a use for them.

ACT-Style Questions: Feathers and Linked Figures 📋

Questions 1–2 refer to the feather passage above. Questions 3–4 use the tables below.

Table 1: Pond water temperature during one evening

Table 2: Water temperature and a frog's call rate

Key Takeaways

• Diagnose the difficulty: competing explanations, dense prose, or multiple figures. Each has a method.
• Conflicting Viewpoints: the introduction is common ground; summarize each view in one line; list agreement and disagreement.
• "Support A but NOT B" must fit A and undercut B. Findings that fit both, or neither, are wrong.
• Opposite predictions mean a result cannot support both views.
• Reading passages that weigh theories: track who holds each view, what evidence each cites, and the author's lean.
• Dense prose: label terms, read topic sentences closely, and let the question aim your rereading.
• Two figures: find the shared variable, carry its value across, and interpolate between rows.

⏱️ Score Improvement Plan

Part 5 of 7 — Pacing, Skipping Smartly, and Learning From Your Misses

Knowing how to read a passage is half the job. The other half is getting to every question with enough time to answer it. This part gives you the pacing math for both tests and a system for turning practice-test mistakes into points.

The Pacing Math

Reading: a common split is about 3 to 4 minutes reading and mapping the passage, then about 6 minutes for its nine or so questions. Natural-science passages often reward a slightly faster first read, because many questions are detail look-ups you can find with your paragraph map.

Science: count the passages when you start. If you want a review reserve, subtract it first, then divide. Example: with 7 passages and a 5-minute reserve, (40 − 5) ÷ 7 = 5 minutes per passage.

Checkpoints Beat Clock-Watching

Rather than checking the time after every question, set checkpoints:

• Reading: about 10, 20, and 30 minutes elapsed at the end of passages 1, 2, and 3.
• Science: one checkpoint per passage, or at the quarter marks (10, 20, 30 minutes).

Behind-pace check: if you have used T minutes on Q questions, your pace is T ÷ Q minutes per question. Multiply by the questions left and compare to the minutes left. If you need more time than you have, speed up now, while there are still easy questions to protect.

Example: 40-minute section, 40 questions. After 16 questions you have used 22 minutes. Pace = 22 ÷ 16 ≈ 1.38 min per question. The remaining 24 questions would need about 33 minutes, but only 18 remain, so you are about 15 minutes short.

To find a target pace for what remains, convert to seconds: 15 minutes left for 20 questions is 900 ÷ 20 = 45 seconds per question.

Skip, Guess, Mark, Return

The ACT has no penalty for wrong answers, so never leave a question blank.

1. Cap your time. If a question passes about 60 to 90 seconds with no clear path, stop.
2. Guess your best remaining choice (eliminate what you can first).
3. Mark it to revisit.
4. Move on to questions that are faster, such as single-table look-ups.
5. Return with your reserve time.

Pushing on until you feel certain is the most expensive habit on both tests. One stubborn question can cost the time for three easy ones.

Question-First Scanning When Time Is Short

On Science, when a passage has figures and you are behind, read each question first, then go straight to the figure, column, or row it names. Skip the introduction unless a question asks about the method. On Reading, use your paragraph map: key nouns in the question stem tell you which paragraph to reread. Question order within a passage does not reliably run from easy to hard, so do not assume the last question is the easiest or the hardest.

The Error Log: Fix the Biggest Leak First

After each timed practice section, sort every miss into one category:

Then count. The category with the most misses is where the next week of practice should go. A student who loses six questions to time and two to units gains more from pacing drills than from any amount of content review. Re-test, re-count, and move to the next biggest leak.

Worked Examples

Situation: On practice tests, a student finishes the first three Reading passages in 33 minutes and guesses on most of the fourth.

Solution:

1. Target: about 10 minutes per passage, so 30 minutes for three. She is 3 minutes over by the end of passage 3.
2. Fix with checkpoints: 10, 20, and 30 minutes. If she reaches minute 10 with two questions left on passage 1, she guesses, marks them, and moves on.
3. Trim the first read: a paragraph map ("P1 puzzle, P2 method, P3 result, P4 caveat") instead of rereading dense sentences until they feel clear.
4. Result: the fourth passage gets its full 10 minutes, which is worth far more than the two marked questions cost.

Situation: After a timed Science section, a student missed 12 questions: 5 unanswered when time ran out, 3 from wrong units, 2 from conflicting viewpoints, and 2 from rushed look-ups.

Solution:

1. Biggest category: time, 5 of 12.
2. Plan: a per-passage cap with skip-and-return, plus question-first scanning on the last passage.
3. Second priority: units, 3 of 12. Add a five-second "circle the units" step to the figure-first routine.
4. Not the plan: memorizing science facts. None of the 12 misses came from missing outside knowledge.

Pacing Drill ✏️

1. The Reading test gives 40 minutes for 4 passage sets. How many minutes per set?

2. A Science section has 40 minutes and 5 passages. You keep a 5-minute reserve. How many minutes per passage?

3. You have 12 minutes left and 16 questions to go. How many seconds per question can you spend?

Practice: Timing Decisions 🎯

ACT-Style Practice: Build Your Own Plan

Use your most recent timed section. Fill in the counts, then read across.

Weekly cycle: timed section → error log → one-week focus on the biggest leak → timed section again. Track the count in each category, not just your score. A shrinking category is proof the fix is working even before the scale score moves.

ACT-Style Questions: Pace and Plan 📋

Key Takeaways

• Reading: 36 questions in 40 minutes, about 10 minutes per passage set (roughly 3–4 to read and map, 6 for questions).
• Science: 40 questions in 40 minutes. Subtract any reserve, then divide by the number of passages.
• Use checkpoints and the behind-pace check: pace × questions left vs minutes left.
• Never leave a blank. Cap, guess, mark, move on, return.
• Short on time? Read the question first and go straight to the figure or paragraph it names.
• Keep an error log, count by category, and fix the biggest leak first. Outside science facts are rarely the leak.

🛠️ Problem-Solving Workshop

Part 6 of 7 — Predictions, Quick Calculations, and Trap Elimination

This part covers the questions that ask you to go one step beyond the data: predict a value, compute a percent, or choose the conclusion the evidence actually supports. These are where careful students separate from fast guessers.

Predicting From a Pattern

Linear example: a spring stretches 3.0 cm per 100 g, which is 0.03 cm per gram. At 450 g: 450 × 0.03 = 13.5 cm. Check the neighbors: 400 g gives 12.0 cm and 500 g gives 15.0 cm, so 13.5 cm sits between them.

Doubling example: 300 cells, 600, 1,200, 2,400 every 30 minutes. Each step doubles. Two more steps: 4,800, then 9,600. The trap is adding a fixed amount (600 more each step) instead of doubling.

Interpolation shortcut: if a value falls between two rows, the answer must fall between their results. Often that alone eliminates three choices.

Quick Calculations

• Percent = part ÷ whole × 100. 42 of 60 seeds sprouted: 42 ÷ 60 = 0.70 = 70%. Dividing upside down (60 ÷ 42) gives more than 100%, which cannot be a share of a group.
• Change = final − initial. Percent change = change ÷ initial × 100.
• Rate = change ÷ time (or per unit). Rates let you compare intervals of different lengths.
• Units first: 1 g = 1,000 mg. A list of masses in mg compared with "1 gram" requires converting before counting.

Patterns That Are Not Straight Lines

Inverse proportion is a classic trap. If volume goes 5, 10, 15, 20 mL and pressure goes 360, 180, 120, 90 kPa, the drops per 5 mL are 180, 60, and 30. They are not equal. But each doubling (5 → 10, 10 → 20) halves the pressure.

Trap Elimination: Six Wrong-Answer Patterns

Observational vs experimental: If researchers only observed existing conditions (a survey of streams, a count of birds in different forests), the safe conclusion is "X tended to occur with Y." If researchers changed one factor and held the rest constant, a cause-and-effect conclusion becomes reasonable for the conditions tested.

Comparing two effects: to say which of two changes mattered more, compare each against the same baseline trial. A trial where both factors changed at once cannot be credited to either factor alone.

Reading-Section Traps on Science Passages

The same logic applies in natural-science Reading passages:

• Too strong: the passage says a finding "suggests," the choice says it "proves."
• Right detail, wrong researcher: a claim from the second study assigned to the first.
• Reversed cause: the passage says low fat leads to torpor; the choice says torpor leads to low fat.
• Outside knowledge: a true science fact the passage never mentions. If it is not in the text, it is not the answer.

Worked Examples

Question A: Estimate the pressure at 1,500 m.

• 1,500 m is between 1,000 m and 2,000 m, so the pressure is between 90 and 79 kPa. Halfway: about 84.5 kPa.

Question B: If the trend continues, is the pressure at 4,000 m more likely about 62 kPa or about 81 kPa?

• Each 1,000 m lowers pressure by 11, 11, then 9 kPa: steady decrease, slightly shrinking. Another drop of about 8 kPa gives about 62 kPa. A value of 81 kPa would mean pressure rose with elevation, reversing the trend.

A survey of 20 city blocks found that blocks with more street trees had lower summer sidewalk temperatures. No trees were planted or removed during the survey.

Which conclusion is best supported?

• Planting trees on a block will lower its sidewalk temperature. ❌ Correlation as cause: nothing was changed, so the survey cannot show cause.
• Trees are the only factor that controls sidewalk temperature. ❌ Overclaiming: no other factors were studied.
• Blocks with the fewest trees reached the highest temperatures ever recorded in the city. ❌ Beyond the data: no city records were compared.
• Blocks with more street trees tended to have cooler sidewalks. ✅ Matches an observational study exactly.

Practice: Make the Prediction 🎯

Quick Calculations ✏️

1. Four samples weigh 3,200 mg, 950 mg, 1,050 mg, and 700 mg. How many weigh more than 1 gram?

2. A population grew from 250 to 300. What was the percent increase? (Enter a number only.)

3. A gas sample has pressure 180 kPa at 10 mL and 90 kPa at 20 mL, and the pattern is inverse proportion. What is the pressure (kPa) at 40 mL?

ACT-Style Practice: Which Change Mattered More?

Claim: "Starting from Trial 1, adding 4 hours of light increased mass more than doubling the fertilizer did."

Work it before opening the check.

1. Light alone (Trial 1 → Trial 3): 20 → 31 g, +11 g.
2. Fertilizer alone (Trial 1 → Trial 2): 20 → 26 g, +6 g.
3. The claim is supported: 11 g > 6 g.
4. Traps: Trial 4 changed both factors, so its 38 g cannot be credited to light alone. Comparing Trials 2 and 4 (+12 g) measures light's effect, but not from the Trial 1 baseline the claim names.

ACT-Style Questions: Trap Elimination 📋

Key Takeaways

• Interpolation: a value between two tested values gives a result between their results.
• Extrapolation: continue the rule. Linear = same change per step; doubling = multiply by 2 each step.
• Percent = part ÷ whole. A share of a group can never exceed 100%.
• Convert units before comparing or counting.
• Non-linear patterns: diminishing returns, a peak "among the levels tested," and inverse proportion (doubling halves; equal steps do not give equal drops).
• Eliminate traps: overclaiming, correlation as cause, wrong column or unit, combined changes, beyond the range, true but irrelevant.
• Compare effects from the same baseline, changing one factor at a time.

🎯 Review & Applications

Part 7 of 7 — Putting It Together: A Natural-Science Reading Passage and a Science Research Summary

This part puts every skill from Parts 1–6 to work on two full-length practice sets: a natural-science Reading passage (36-question test, about 10 minutes per passage) and a Science Research Summary (optional test, 40 questions in 40 minutes). First, a review of the moves that matter most.

Decision Guide: Question Type → First Move

Reading a Natural-Science Passage: The Routine

1. First read (3–4 minutes): label each paragraph's role (phenomenon, puzzle, method, result, interpretation, caveat). Note each technical term with a short label.
2. Notice the author's voice: words such as remarkable, tempting, premature, or remains unclear will answer attitude questions.
3. Answer from the map: go back to the paragraph a question points to and reread only the sentences you need.
4. Match the hedges: if the passage says may or in laboratory trials, the right answer keeps that limit.

Reading a Research Summary: The Routine

1. Read the purpose sentence and each experiment's setup quickly, and build the changed / measured / same table for each experiment.
2. Scan each table: title, columns, units, trend.
3. Look for a shared trial. When two experiments share a condition (same salinity and same temperature), that trial is your baseline for comparing the two factors, and its results should match across experiments.
4. Answer, pointing at a row for every choice you select.

Final Score-Building Checklist

• Reading pace: checkpoints at about 10, 20, and 30 minutes.
• Science pace: (40 − reserve) ÷ number of passages, checkpoint after each passage.
• No blanks: cap, guess, mark, move on, return.
• After each practice test: error log, count by category, fix the biggest leak first.
• Two habits for both tests: point to evidence for every answer, and never let a choice claim more than the passage or data do.

Worked Example: One Question, Every Skill

Setup: In Experiment 1, students measured how far a paper airplane flew with wings of 10, 15, and 20 cm at a launch angle of 10°: 6.2 m, 8.0 m, and 7.1 m. In Experiment 2, they kept the wings at 15 cm and changed the launch angle to 5°, 10°, and 15°: 7.4 m, 8.0 m, and 6.5 m.

Question: Starting from the 15 cm, 10° design, which single change shortened the flight more: switching to 20 cm wings, or raising the angle to 15°?

Solution:

1. Find the shared trial. 15 cm at 10° appears in both experiments, and both report 8.0 m. That is the baseline.
2. Change one factor at a time from the baseline. Wings to 20 cm: 8.0 → 7.1 m, a drop of 0.9 m. Angle to 15°: 8.0 → 6.5 m, a drop of 1.5 m.
3. Compare: raising the angle shortened the flight more.
4. Trap check: the longest flight in either experiment (8.0 m) is not the question. And the data cannot predict a 20 cm, 15° airplane, because no trial changed both factors.

Practice Set 1: Natural-Science Reading Passage 🎯

Give yourself about 6 minutes for the passage and five questions.

(1) Each winter in the northern forests of North America, the wood frog does something that would kill most animals: it freezes. Ice forms beneath its skin and around its organs, its heart stops, and it stops breathing. Yet when the ground thaws in spring, the frog's heart starts beating again and within a day the animal hops away.

(2) The key is where the ice forms. Ice crystals that grow inside cells puncture their delicate membranes, and cells damaged this way do not recover. The wood frog survives because ice forms in the spaces between its cells, while the cells themselves stay liquid. As ice begins to form on the frog's skin, its liver rapidly breaks down stored glycogen, a starch-like fuel, into glucose and floods the blood with it. The glucose acts as a cryoprotectant, a substance that keeps the fluid inside cells from freezing by lowering its freezing point and limiting how much water the cells lose.

(3) In laboratory trials, researchers have found that the speed of freezing matters. Frogs cooled slowly, over many hours, built up far more glucose in their tissues than frogs cooled quickly, and slowly cooled frogs were much more likely to revive. The likely explanation is simple: the liver needs time to release enough glucose before ice spreads inward.

(4) Some medical researchers hope that the frog's chemistry might one day help preserve human organs for transplant, which currently survive only hours outside the body. The idea is appealing, but it is far from realized. A frog's tissues have evolved over many generations to tolerate freezing; a human kidney has not, and adding glucose alone has not been shown to protect it. For now, the wood frog is less a recipe than a reminder that the line between frozen and alive is not where we once drew it.

First Move Check 🔍

Practice Set 2: Science Research Summary

Give yourself about 5 minutes for this passage and the five questions that follow.

Students studied how water conditions affect the hatching of brine shrimp eggs.

Experiment 1: Five dishes each received 200 eggs in salt water of a different salinity. All dishes were kept at 25 °C under the same light. After 48 hours, the students counted the hatched shrimp and calculated the percent hatched.

Experiment 2: Four dishes each received 200 eggs in salt water at 30 g/L. The dishes were kept at different temperatures under the same light. After 48 hours, the students calculated the percent hatched and also recorded how many hours passed before the first shrimp hatched.

Before you answer: build the table for each experiment. Experiment 1 changes salinity, measures percent hatched, and keeps temperature (25 °C), light, egg count, and time the same. Experiment 2 changes temperature and keeps salinity at 30 g/L. The shared trial is 30 g/L at 25 °C, and both experiments report 88% for it.

ACT-Style Questions on the Brine Shrimp Study 📋

Key Takeaways

• Natural-science Reading: map paragraph roles, read terms in context, follow cause and effect, and match the author's hedges and attitude.
• Science Research Summaries: build the changed / measured / same table for every experiment before answering.
• Shared trials are baselines. Compare each factor by changing it alone from the shared condition.
• Peaks and limits: say "among the levels tested," and interpolate between neighboring rows.
• Percent of a group: percent × total. Watch for the complement trap (the number that did not hatch).
• Every answer needs a pointer: a sentence, a row, or a data point. If you cannot point to it, eliminate it.
• Keep the cycle going: timed practice → error log → fix the biggest leak → timed practice.