OAR common mistakes
OAR · Understand the traps and how to avoid them.
Reads a multi-step word problem and immediately starts doing the arithmetic in their head, keeping intermediate values (a converted rate, a partial total, a remainder) only in working memory.
The math section is tightly timed, so candidates try to save seconds by skipping written setup - but head-only arithmetic is where a dropped digit or forgotten remainder turns a solvable problem into a wrong answer, and it cannot be checked afterward.
What to do instead
Force one line of written setup per problem: a labelled expression or short equation showing the operation before the number. Keep a dedicated scratch column on the page so every problem has visible work you can re-read in five seconds. Never let two operations pass without writing the intermediate result.
Plugs numbers into a formula or proportion without first converting units, mixing hours with minutes, feet with inches, or a percentage with its decimal form.
Word problems deliberately bury the mismatch in prose ('a pump moves 40 gallons per minute... how many gallons in 3 hours?'), and under time pressure the familiar-looking numbers get used as-is.
What to do instead
Before any calculation, rewrite every quantity in the problem with its unit written out, then convert everything to a single consistent unit set in a separate step. If the question asks for an answer in specific units, convert back as the final step and confirm the unit label matches what was asked.
Sets up a ratio or rate comparison with the terms in the wrong order - matching 'miles' against 'hours' on one side of a proportion instead of keeping like units diagonal.
Candidates memorize 'cross multiply' but not the structural rule that both sides must represent the same ratio, so a plausible-looking equation gets solved correctly and produces a wrong answer.
What to do instead
Write the ratio with units attached (e.g. gallons/min = gallons/min) and check that the units on each side cancel to the same thing before solving. If the units don't cancel to a clean result, the setup is inverted - flip it before doing arithmetic.
Grinds through algebraic setup on a problem when the five answer choices could have been tested directly, spending two to three minutes on a question designed to be back-solved in forty seconds.
Candidates default to the method they learned first (formal equation) and don't scan the answer choices before starting, so they never notice that plugging in values is faster.
What to do instead
Make a habit of reading the answer choices before writing any algebra. If the choices are numerical and the problem is a 'find the value' type, test the middle choice first and use the result to eliminate half the options in one pass. Reserve formal setup for problems where the choices contain variables.
Spends four or more minutes on an early hard problem to protect a streak, then has to rush the final third of the section and guesses on questions they could have solved.
Timed sections create a sunk-cost trap: the effort already invested makes abandoning the problem feel like waste, and there is no visible clock discipline planned in advance.
What to do instead
Adopt a two-pass rule: on the first pass, any problem not cracked within roughly 75 seconds gets marked and skipped. Finish every remaining question before returning to marked items. Practice with a visible timer so the 75-second cutoff becomes automatic rather than a conscious decision under stress.
Answers a question using what they know or believe about the topic - a Navy procedure, a historical event, a safety rule - rather than what the passage actually states.
The passages are often on military or technical subjects where candidates have prior exposure, so a familiar-sounding option feels correct even when the passage says something narrower or different.
What to do instead
For every answer selected, point to the specific sentence or phrase in the passage that supports it. If you cannot locate supporting text, the option is wrong regardless of whether it is true in the real world. Treat outside knowledge as inadmissible evidence.
Picks an option that is factually supported by the passage but does not answer the question asked - a true detail when the question asked for the main idea, or a broad summary when the question asked about a specific cause.
Under time pressure candidates match on keyword overlap rather than on the question's demand, and a supported-but-off-target option is the most seductive distractor on the section.
What to do instead
Before reading the choices, restate the question to yourself in a few words ('what is the author's main point', 'why did X happen'). Then check each candidate against that restatement - not against whether it appears in the passage. Match scope as well as content: a main-idea answer must cover the whole passage, not one paragraph.
Chooses the strongest-worded option on tone, inference, or attitude questions - the one containing 'always', 'never', 'entirely', or 'proves' - because it sounds more decisive.
Academic and technical prose is usually hedged, but decisive language reads as more confident, so candidates confuse certainty of phrasing with correctness of content.
What to do instead
Treat absolute qualifiers as an elimination flag: strike any option with 'always', 'never', 'all', 'none', or 'proves' unless the passage itself uses equally absolute language. Prefer the option whose strength matches the passage's own hedging ('suggests', 'tends to', 'in most cases').
Determines the direction two pulleys or gears turn by glancing at the diagram and assuming both rotate the same way, or counts a belt-driven pair as reversing direction.
Candidates reason from the visual layout instead of applying the transmission rule, and the two cases look nearly identical on paper.
What to do instead
Apply the rule explicitly: meshed gears and pulleys sharing a belt turn in opposite directions; pulleys on a common shaft, or connected by a crossed belt, turn the same direction. Trace the chain one link at a time from the driver and state the direction out loud or in a note before answering.
Computes torque or mechanical advantage using the full length of a lever, or the distance between the two applied forces, instead of the distance from the fulcrum to each force.
The lever is drawn end to end, so the total length is the most visually salient measurement, and the fulcrum's off-center position is easy to overlook.
What to do instead
Before calculating, mark the fulcrum on the diagram and measure both moment arms from that point outward, separately for effort and load. State the balance condition as (effort × effort arm) = (load × load arm) with each arm sourced from the fulcrum, never from the opposite end of the bar.