- Subject-verb agreement
- A verb must match its subject in number — a singular subject takes a singular verb. Cross out the phrase between subject and verb to find the true subject.
- Independent clause
- A group of words with a subject and verb that can stand alone as a complete sentence.
- Dependent (subordinate) clause
- A clause with a subject and verb that cannot stand alone (e.g., 'because she left').
- Comma splice
- The error of joining two independent clauses with only a comma. Fix with a period, semicolon, or comma + FANBOYS conjunction.
- FANBOYS
- The seven coordinating conjunctions — For, And, Nor, But, Or, Yet, So — that join two independent clauses when preceded by a comma.
- Semicolon
- Joins two closely related independent clauses without a conjunction. It works wherever a period would.
- Colon
- Introduces a list, explanation, or quotation — but only after a complete sentence.
- Dangling modifier
- A descriptive phrase with no clear word to modify, so it seems to describe the wrong noun.
- Misplaced modifier
- A modifier placed next to the wrong word, changing the intended meaning.
- Parallel structure
- Items in a list, comparison, or series share the same grammatical form (reading, writing, and running).
- Pronoun-antecedent agreement
- A pronoun must match the noun it refers to in number and gender, and the reference must be clear.
- Its vs. it's
- 'Its' is the possessive of it (no apostrophe); 'it's' is the contraction of 'it is' or 'it has.'
- Their / there / they're
- Their = possessive; there = place; they're = they are.
- Your vs. you're
- Your = possessive; you're = you are.
- Than vs. then
- 'Than' compares (faster than); 'then' refers to time or sequence (and then).
- Who vs. whom
- Who is a subject (who is calling?); whom is an object (to whom did you give it?).
- Apostrophe use
- Shows possession (the student's score) or a contraction (it's = it is) — never a plural.
- Conventions of Standard English
- The English reporting category covering grammar, usage, punctuation, and sentence structure.
- Knowledge of Language
- The English reporting category covering precise word choice, style, tone, and concision.
- Production of Writing
- The English reporting category covering topic development, organization, unity, and cohesion (including transitions).
- Concision
- Saying the same thing in fewer words. When two choices are both grammatical, the shorter, clearer one usually wins.
- Redundancy
- Repeating an idea unnecessarily (e.g., 'return back,' 'each and every'). The PreACT wants you to cut it.
- Transition word
- A word like however, therefore, or for example that signals the logical relationship between sentences.
- Subjunctive mood
- Used for hypothetical or wishful statements: 'If she were here…' (not 'was').
- Run-on sentence
- Two independent clauses joined with no punctuation or conjunction.
- Sentence fragment
- An incomplete sentence missing a subject, a verb, or a complete thought.
- NO CHANGE
- The PreACT English answer choice meaning the underlined text is already correct — it's right a fair share of the time.
- Verb tense consistency
- Keep verb tenses consistent within a passage unless the timeline clearly shifts.
- Slope
- The steepness of a line, change in y over change in x (rise over run); m in y = mx + b.
- Slope formula
- m = (y₂ − y₁) / (x₂ − x₁) for a line through two points.
- Slope-intercept form
- y = mx + b, where m is the slope and b is the y-intercept.
- Parallel lines (slopes)
- Parallel lines have equal slopes.
- Perpendicular lines (slopes)
- Perpendicular slopes are negative reciprocals (slope 2 → slope −1/2).
- Pythagorean theorem
- For a right triangle, a² + b² = c², where a and b are the legs and c is the hypotenuse.
- Pythagorean triples
- Whole-number right-triangle side sets to memorize: 3-4-5 and 5-12-13.
- Distance formula
- d = √[(x₂ − x₁)² + (y₂ − y₁)²] — the distance between two points.
- Midpoint formula
- M = ((x₁ + x₂)/2, (y₁ + y₂)/2) — the midpoint of a segment.
- Triangle angle sum
- The interior angles of any triangle add up to 180°.
- Area of a triangle
- A = ½ · base · height.
- Area of a rectangle
- A = length × width.
- Perimeter of a rectangle
- P = 2(length + width).
- Area of a circle
- A = πr², where r is the radius.
- Circumference of a circle
- C = 2πr (or πd), where r is the radius and d the diameter.
- Volume of a rectangular solid
- V = length × width × height.
- Mean
- The average — the sum of the values divided by how many there are.
- Median
- The middle value of an ordered data set (average the two middle values if the count is even).
- Mode
- The value that appears most often in a data set.
- Outlier effect on center
- An outlier pulls the mean toward it but barely moves the median.
- Probability
- Favorable outcomes ÷ total outcomes — a value from 0 (impossible) to 1 (certain).
- Proportion
- An equation stating two ratios are equal (a/b = c/d); solve by cross-multiplying.
- Ratio
- A comparison of two quantities, like 3 cups flour to 2 cups sugar (3:2).
- Percent
- A part per 100. To find a percent of a number, convert to a decimal and multiply (25% = 0.25).
- Percent decrease
- If something is x% off, it now costs (100 − x)% of the original; solve for the original by dividing.
- Function
- A rule assigning exactly one output (y) to each input (x); written f(x).
- Evaluating f(x)
- Substitute the input value for x and simplify to get the output.
- Linear equation (solving)
- Isolate the variable by doing the same operation to both sides, then check by substitution.
- Inequality sign flip
- When you multiply or divide both sides of an inequality by a negative number, flip the inequality sign.
- System of equations
- Two equations solved together; use substitution or elimination (add/subtract) to find the shared solution.
- Exponent rule (product)
- xᵃ · xᵇ = xᵃ⁺ᵇ — add exponents when multiplying like bases.
- Exponent rule (power)
- (xᵃ)ᵇ = xᵃᵇ — multiply exponents when raising a power to a power.
- Scientific notation
- A number written as a × 10ⁿ with 1 ≤ a < 10, used for very large or small numbers.
- GCD (greatest common divisor)
- The largest integer that divides two numbers evenly (GCD of 36 and 54 is 18).
- Order of operations (PEMDAS)
- Parentheses, Exponents, Multiplication/Division (left to right), Addition/Subtraction (left to right).
- y-intercept
- Where a line crosses the y-axis; the b in y = mx + b (set x = 0).
- x-intercept
- Where a line crosses the x-axis (set y = 0 and solve for x).
- Main idea
- The central point the whole passage supports — broader than any single detail.
- Inference
- A conclusion the passage implies but does not state directly, supported by textual evidence.
- Vocabulary in context
- A word's meaning from how it's used in the passage — often a less common, secondary meaning.
- Author's tone
- The author's attitude toward the subject, shown through word choice (critical, admiring, neutral, skeptical).
- Author's purpose
- Why the author wrote the passage — to inform, persuade, describe, or entertain.
- Point of view
- The perspective from which a passage is written (first person, third person, an author's stance).
- Supporting detail
- A specific fact or example in the passage that backs up a larger point.
- Key Ideas and Details
- The largest Reading category: main ideas, summary, sequence, and supporting evidence.
- Craft and Structure
- The Reading category covering word meaning, point of view, text structure, and tone.
- Integration of Knowledge and Ideas
- The Reading category covering arguments, evidence, and connecting information across a passage.
- Textual evidence
- The specific lines that prove an answer — answer detail and inference questions from the text, not memory.
- Theme
- The underlying message or insight a literary passage explores (e.g., resilience, heritage).
- Metaphor
- A comparison that states one thing is another ('a melting pot of cultures') to convey an idea.
- Paired passages
- Two shorter passages on one topic; summarize each author first, then compare their views.
- EXCEPT / LEAST questions
- Three answers are supported and one isn't — cross off what you can prove from the text.
- Summary
- A brief statement of the passage's main points in your own words.
- Reading pacing strategy
- Budget your time across the passages so you finish; don't get stuck on one hard question.
- Prose fiction / literary narrative
- A Reading passage type drawn from short stories or novels, focused on character and theme.
- Natural science passage
- A nonfiction Reading passage about a scientific topic, focused on information and explanation.
- Independent variable
- The factor the experimenter deliberately changes (usually the x-axis).
- Dependent variable
- The outcome measured in response to the independent variable (usually the y-axis).
- Control group
- The group that receives no experimental treatment — the baseline for comparison.
- Constant (controlled variable)
- A factor held the same so it doesn't affect the result.
- Hypothesis
- A testable proposed explanation a scientist sets out to support.
- Data Representation
- A Science passage format presenting graphs and tables to interpret.
- Research Summaries
- A Science passage format describing one or more related experiments to compare.
- Conflicting Viewpoints
- A Science passage format presenting two or more competing explanations to compare.
- Interpolation
- Estimating a value between known data points on a trend.
- Extrapolation
- Extending a trend to estimate a value beyond the known data points.
- Direct relationship
- As one variable increases, the other increases.
- Inverse relationship
- As one variable increases, the other decreases.
- Reading a graph (Science)
- Check axis labels and units first, then locate the value and read straight across.
- Science section strategy
- Read the figures before the text; most questions are answered straight from the graphs and tables.
- Interpretation of Data
- The largest Science skill area: reading values, trends, and relationships from figures.
- Scientific investigation
- The Science skill area about experimental design — variables, procedures, and controls.
- Evaluation of results
- The Science skill area about judging hypotheses, predictions, and conclusions.
- Specific heat capacity
- The energy needed to raise a substance's temperature; water's is high due to hydrogen bonding.
- Photosynthesis
- The process where plants use chlorophyll to absorb sunlight and make energy from CO₂ and water.
- Decomposers
- Organisms that recycle nutrients by breaking down dead matter in an ecosystem.
- Most abundant atmospheric gas
- Nitrogen makes up about 78% of Earth's atmosphere.
- pH scale
- A 0–14 scale measuring hydrogen-ion concentration; below 7 is acidic, above 7 is basic.
- Plate tectonics
- The movement of Earth's crustal plates; subduction zones are where crust is destroyed.
- Earth's outer core
- The liquid layer whose motion generates Earth's magnetic field.
- Evaporation
- The process moving water from the surface into the atmosphere in the water cycle.
- Genetic mutation
- A change in a DNA sequence, often from errors during DNA replication.
- Food chain
- A model showing how energy passes from producers to consumers to decomposers.
- PreACT
- ACT's practice test for grades 9–10. Covers English, Math, Reading, and Science on a 1–35 scale and predicts a future ACT score.
- PreACT Composite score
- The main PreACT score, 1–35. For 2025–2026, the average of the English, Math, Reading, and Science section scores, rounded to a whole number.
- PreACT score scale
- Each section and the Composite are scored 1–35 (the ACT uses 1–36).
- PreACT STEM score
- The average of your Math and Science scores — an early read on STEM readiness.
- PreACT ELA score
- On some reports, the average of your English and Reading scores, summarizing English/Language Arts readiness.
- Predicted ACT score
- A range reported with each PreACT score that estimates how you'd likely score on the ACT later in high school.
- PreACT Readiness Benchmark
- The section score signaling you're on track to be ready for entry-level college courses in that subject.
- Who takes the PreACT?
- Students in grades 9–10, as early, low-stakes practice before the official ACT.
- PreACT sections
- English, Mathematics, Reading, and Science — the same four subjects as the ACT.
- Number of PreACT questions
- About 136 multiple-choice questions: English 45, Math 36, Reading 25, Science 30.
- PreACT total testing time
- Just over two hours (roughly 2 hours 10 minutes), varying slightly by PreACT version.
- PreACT vs. ACT
- The PreACT (grades 9–10, scored 1–35) is the practice version that predicts the ACT (grades 11–12, scored 1–36), which is the test colleges actually see.
- Does the PreACT go to colleges?
- No. The PreACT is practice and prediction only; it is not sent to colleges.
- Test maker of the PreACT
- ACT, Inc. — the same organization that makes the ACT.
- PreACT calculator policy
- A permitted calculator may be used on the entire Math section.
- PreACT Composite change in fall 2026
- Starting fall 2026, the PreACT Composite is planned to be the average of English, Math, and Reading only (Science reported separately).
- PreACT answer choices
- Every question is multiple choice with four answer choices.
- Why take the PreACT?
- To get a realistic ACT experience, find weak spots early, and receive a predicted ACT score — ACT's research shows takers average ~1 Composite point higher on the ACT.