Most ACT common mistakes have nothing to do with intelligence or knowledge — they stem from poor pacing, sloppy habits, and avoidable test-day blunders. With roughly 1.4 million students taking the ACT each year and the national average sitting at just 19.4 out of 36, small fixes can mean big score gains. Here are the mistakes that cost students the most points and exactly how to avoid each one.
Running out of time is the single most common reason students score lower than expected on the ACT. The enhanced ACT format packs 131 core questions into just 2 hours and 5 minutes — that leaves less than a minute per question on average. Students who do not pace themselves leave easy points unanswered at the end of every section.
| Section | Questions | Time Limit | Seconds Per Question | Pacing Tip |
|---|---|---|---|---|
| English | 50 | 35 min | ~42 sec | Flag grammar-trap questions and return |
| Math | 45 | 50 min | ~67 sec | Skip hard questions past #35 on first pass |
| Reading | 36 | 40 min | ~67 sec | Spend 8-9 min per passage + questions |
| Science (optional) | 40 | 40 min | ~60 sec | Go straight to questions, refer back to data |
Each ACT section demands a different pace. English is the tightest at roughly 42 seconds per question, while Math and Reading give you about 67 seconds each. Before test day, practice with a timer set to these intervals. If you consistently run over, reduce the number of questions you attempt on your first pass and save the hardest ones for the end.
Every ACT question is worth the same number of points regardless of difficulty. Spending three minutes wrestling with one hard question costs you time for three easier questions you could answer correctly. If a question has you stuck for more than 30-60 seconds, mark it in your test booklet and move on. Return to skipped questions only after you have answered everything within reach.
Wear an analog watch (smartwatches are prohibited) and set pacing checkpoints: for English, you should be at question 25 by the 17-minute mark. For Math, aim to reach question 30 by the 35-minute mark. These checkpoints give you an early warning if you are falling behind.
Enter the number of questions you plan to attempt in each section to see your target time per question.
Even students who know the material well lose significant points to careless mistakes. Misreading questions, bubbling errors, and mental math shortcuts are the most common culprits — and they are entirely preventable with the right habits.
| Mistake Category | Frequency | Estimated Point Impact | Fix Difficulty |
|---|---|---|---|
| Time management | Very common | 3-5 points | Moderate — requires practice |
| Careless errors | Very common | 2-4 points | Moderate — build habits |
| English grammar traps | Common | 2-3 points | Easy — learn the rules |
| Math calculation errors | Common | 2-4 points | Moderate — write out work |
| Leaving blanks | Common | 1-3 points | Easy — just guess |
| Reading/Science misreads | Common | 2-3 points | Moderate — practice strategy |
| Test day prep failures | Occasional | 1-5 points | Easy — plan ahead |
Your brain's short-term memory is limited, especially under time pressure. Doing mental math or reasoning through a complex passage question in your head invites errors. Write down every calculation step on scratch paper. For reading questions, jot down the line numbers where you found evidence. This creates a trail you can double-check in seconds.
Misreading question stems is one of the most frustrating mistakes because you knew the right answer — you just answered the wrong question. Keywords like NOT, EXCEPT, and LEAST flip the entire meaning of a question. Get into the habit of underlining these reversal words every time you see them.
Bubbling errors are equally devastating. If you skip a question in your test booklet but forget to skip it on the answer sheet, every subsequent answer shifts to the wrong line. Periodically check — at least every 10 questions — that your question number matches your answer sheet row.
Worked Example
A student reads an ACT question that asks: "Which of the following is NOT supported by the passage?" The student quickly finds an answer that IS supported and selects it.
The ACT English section is built around predictable grammar traps. Students who rely on how an answer "sounds" rather than applying actual grammar rules fall for these traps consistently. Learning the five most common patterns can boost your English score by 2-3 points.
| Grammar Trap | What Students Do Wrong | The Correct Rule |
|---|---|---|
| Unnecessary commas | Add commas wherever they hear a pause | Only place commas where grammar rules require them — never between subject and verb |
| Redundancy/wordiness | Pick the longest, most detailed answer | The ACT rewards concise writing — the shortest correct answer often wins |
| Subject-verb agreement | Match verb to the nearest noun | Ignore interrupting phrases — match verb to the actual subject |
| NO CHANGE trap | Accept the underlined text because it looks fine | Always check all four answer choices before selecting NO CHANGE |
| Dangling modifiers | Don't check what the modifier actually describes | The subject being modified must immediately follow the modifying phrase |
The ACT loves to test whether you can distinguish between grammatically necessary commas and decorative ones. Students tend to insert commas wherever they hear a natural pause in speech, but spoken English and written English follow different rules. Never place a comma between a subject and its verb, and always check whether a comma actually separates an independent clause, introduces a list, or sets off a nonrestrictive clause before accepting it.
When you see four answer choices and one is noticeably shorter than the others, pay close attention — the shortest option is often correct on the ACT English section. The test deliberately includes wordy, redundant phrasing to tempt students who think longer answers sound more "formal" or "complete." If two words mean the same thing in a phrase (like "past history" or "advance planning"), the shorter version wins.
This is one of the ACT's favorite tricks. A sentence will place a prepositional phrase or relative clause between the subject and the verb, making it easy to match the verb to the wrong noun. Train yourself to mentally cross out everything between the subject and the verb, then check whether they agree in number.
Worked Example
An ACT English question underlines: "The results of the experiment, which lasted three years, was published in a major journal." Most students read past this without noticing the error.
ACT math mistakes rarely come from not understanding the concept — they come from rushing, skipping steps, and solving for the wrong thing. The ACT provides no formula sheet, so you also need at least 10 key formulas memorized before test day.
Unlike the SAT, the ACT does not give you a reference sheet. You need to have the quadratic formula, area formulas for circles and triangles, the Pythagorean theorem, slope formula, SOHCAHTOA trigonometric ratios, and the distance/midpoint formulas committed to memory. Missing even one of these can cost you multiple questions.
Create a formula sheet during your study phase and quiz yourself regularly. On test day, some students write down key formulas in the margins of their test booklet as soon as the section starts — a smart way to offload memory and reduce anxiety.
This is one of the most common math traps on the ACT. A question will ask for "2x" or "x + 2," and the answer choice for plain "x" will be right there waiting to trick you. Always read the final line of the question one more time after solving to make sure you are answering what was actually asked.
Worked Example
An ACT math question states: "If 4x - 8 = 12, what is the value of 2x + 3?" A student quickly solves for x and selects that answer.
The ACT Reading and Science sections test your ability to interpret text and data precisely. The most common ACT test mistakes to avoid in these sections involve adding outside knowledge and misreading visual data.
On ACT Reading, the correct answer always reflects exactly what the passage says — never what you know from a class, a textbook, or common sense. Many wrong answers are designed to sound reasonable based on general knowledge but contain one detail that the passage never actually states. If you need outside knowledge to justify an answer, it is probably wrong.
Train yourself to find the specific line or paragraph that supports your answer. If you cannot point to it in the text, you are relying on inference or assumption — and the ACT punishes that.
In the Science section, misreading axis labels on graphs is one of the most frequent mistakes. Before looking at any data point, read the title, the x-axis label, the y-axis label, and the units. Students who skip this step often report the right number from the wrong axis or misinterpret the scale.
Focus on overall trends rather than individual data points unless the question specifically asks about a single value. The ACT often includes answer choices that cherry-pick one outlier data point to mislead you into thinking a trend goes the opposite direction.
The ACT has no penalty for wrong answers — you earn points for correct answers and lose absolutely nothing for incorrect ones. Yet many students still leave questions blank, throwing away free points. This is one of the easiest ACT common mistakes to fix.
A random guess on a four-choice question gives you a 25% chance of getting it right. That is not great odds, but it is infinitely better than the 0% chance you get from a blank answer. If you can eliminate even one wrong choice, your odds jump to 33%. Eliminate two, and you are at 50%. There is no mathematical scenario in which a blank answer is the better choice on the ACT.
Before test day, pick a consistent "guessing letter" for questions you have to skip completely — for example, always bubble C for blind guesses. This removes decision fatigue and ensures you never leave a blank. For questions where you can do partial work, use process of elimination first: cross out obviously wrong answers, then guess from the remaining options. Even eliminating one choice meaningfully improves your odds.
Many students undermine their ACT performance before the test even begins. Cramming the night before, skipping breakfast, and arriving flustered at an unfamiliar test center are all avoidable ACT test day mistakes that can silently cost you points.
Sleep is crucial to memory retrieval and focus. Studying all night before the ACT does far more harm than good — your brain consolidates information during sleep, so a well-rested student with moderate preparation will outperform an exhausted student who crammed. Aim for 8 or more hours of sleep. In the morning, eat a balanced, protein-rich breakfast to sustain energy. Avoid sugary foods that cause energy crashes mid-test.
Start your consistent study routine 2-3 months before the test, not the week before. Students who tested multiple times improved their ACT Superscore by an average of 2.4 points — evidence that steady practice, not last-minute cramming, drives improvement.
Pack everything the night before so you are not scrambling in the morning. You need your photo ID (matching your registration name), printed admission ticket, an approved calculator with fresh batteries, multiple #2 pencils, a good eraser, and a watch without internet or alarm capability. Smartwatches and fitness bands are prohibited. Bring healthy snacks and water for the break — protein-rich options like nuts or cheese prevent energy crashes.
If possible, do a practice drive to the test center a few days beforehand. Knowing exactly where to park and which building to enter eliminates one source of test-morning anxiety.
No, the ACT has no guessing penalty. You earn points for correct answers and lose nothing for wrong answers, so you should always fill in an answer for every question, even if you need to guess randomly. Leaving any question blank is one of the most common and costly ACT mistakes.
Time per question varies by section. English gives about 42 seconds per question (50 questions in 35 minutes), Math about 67 seconds (45 questions in 50 minutes), and Reading about 67 seconds (36 questions in 40 minutes). The optional Science section gives about 60 seconds per question.
The most common ACT English mistakes include adding unnecessary commas, choosing the longest answer choice when a shorter one eliminates redundancy, relying on how answers sound rather than grammar rules, defaulting to NO CHANGE without checking alternatives, and missing misplaced or dangling modifiers.
Write down all your work on scratch paper rather than doing mental math. Read each question stem carefully, underlining key words like NOT or EXCEPT. Periodically verify your answer sheet bubbles match your question numbers. Practice under timed conditions regularly to build accuracy under pressure.
Yes. If a question has you stuck for more than 30-60 seconds, mark it and move on. Every question on the ACT is worth the same number of points, so spending three minutes on one hard question means losing time for three easier questions you could answer correctly. Return to skipped questions if time permits.