Why Pearson Mastering Marks an Answer Wrong: Rounding, Units, and Answer Formats

Pearson Mastering usually marks an answer wrong for one of three reasons: the number falls outside the grading tolerance (often because you rounded too early), the unit is missing or wrong, or the answer was typed in a format Mastering reads differently than you intended. The physics or chemistry behind your answer can be perfectly sound and still score zero if you type 1.23e5, write 2ab instead of 2*a*b, or put cos(30) when the system expects radians. Each of these has a specific fix, and some of them don't even cost you an attempt.

This guide explains how Mastering Chemistry, Mastering Physics and the other Mastering courses grade answers, walks through original practice examples that reproduce the most common "wrong" answers, and shows how to fix each one. The grading rules come from Pearson's own help documentation. Remember that instructors can change many of the defaults described here, so check your course's grading policy as well.

Quick Diagnosis: What Your Mastering Feedback Means

How Pearson Mastering Grades a Numeric Answer

Mastering does not check whether your number matches its answer digit for digit. It checks whether your number falls inside a tolerance band around the correct value. Pearson's student guide to grading tolerance says "the typical grading tolerance for most numeric answers in Mastering assignment questions is within 2% or 3%." With a 2% tolerance and a correct answer of 100, any answer from 98 to 102 is accepted.

A few details from Pearson's instructor documentation explain what students often misread as a significant figures penalty:

• The default tolerance is 2.00%, and instructors or question authors can tighten or loosen it.
• When a question specifies no significant figures, Mastering formats its answer to 3 significant figures by default.
• Pearson states that "the number of significant figures… a student enters in their answer is NOT graded by the system." What matters is whether the value lands in the accepted range.
• Questions that require four significant figures are stricter. Pearson notes that "a 0.1% - 0.9% tolerance is typical when four significant figures are required."

Around that band, Mastering uses two feedback zones. If your answer is just outside the rounded range but close to the full-precision answer, you see "Very close," and Pearson's authoring guide says no points are deducted. If your answer is a little further away, within about 5% of the formatted answer but not close to the precise value, you see "Not quite," and you lose an attempt and any credit attached to it.

Rounding Errors: The Most Common Reason a Right Method Gets Marked Wrong

Pearson's guide is blunt about it: "Rounding too early can cause your final answer to be outside of the allowed tolerance range, even if you have otherwise calculated correctly!" Rounding causes the most trouble when a problem subtracts two numbers of similar size, because a small rounding difference becomes a large share of a small result.

Worked Example: Rounding Too Early in a Kinematics Problem

Practice problem. A ball is thrown straight up at 12.0 m/s. What is its speed when it is 7.00 m above the launch point? Use g = 9.81 m/s².

The method is v² = v₀² − 2gh, so v² = 144 − 2(9.81)(7.00).

The student who rounded 137.34 to 137 used the right physics and kept three significant figures, yet missed the 2% band, which runs from about 2.53 to 2.63 m/s. The fix is simple: keep every digit your calculator gives you until the final step, and round only the answer you type into Mastering.

Rules for Rounding in Mastering

• Store intermediate results in your calculator's memory instead of retyping rounded values.
• Use the constants the question gives you, such as g = 9.81 m/s² rather than 9.8 or 10. A different constant can shift the answer outside the band.
• Round your final answer to the number of significant figures the question asks for. If it doesn't specify, three is the usual default.
• Be extra careful when a question says to give four significant figures, because the tolerance can drop below 1%.

Unit Errors in Mastering Chemistry and Mastering Physics

When a question asks for both a value and a unit, Pearson's guide to entering values with units tells you to "enter BOTH the value and unit parts." Sometimes the unit is already printed next to the answer box. When it isn't, the unit is part of what gets graded. Pearson's list of acceptable units adds three rules that catch many students:

• Use abbreviations only, with no period. Type kg, not kilograms or kg.
• Units are case-sensitive. mm is a millimeter, Mm is a megameter, and MM is not a unit at all.
• Equivalent units earn full credit. Pearson's example: if the correct answer is 2 V and you enter 2000 mV, you receive full credit.

Whether a unit mistake costs you an attempt depends on whether Mastering recognizes the unit. If it doesn't recognize what you typed, Pearson says "you do NOT lose an answer attempt," and you can fix the spelling. If it recognizes the unit but the unit is wrong, for example 25.0 g when the answer is 25.0 kg, "you lose an answer attempt and any associated credit." And if the question specifies a unit system, answering in a different system costs an attempt "even if your answer would otherwise be considered equivalent."

Answer Format Errors That Change What Mastering Reads

Scientific Notation: Avoid the Letter E

This is the most expensive habit students bring from calculators and spreadsheets. Pearson's guide to entering math says to use scientific notation, "not e (which Mastering evaluates as the constant 2.718...) or E. For example, enter 1.23*10^5 instead of 1.23e+5 or 1.23E+5." Typing Avogadro's number as 6.022e23 gives Mastering an expression built from the constant e, not 6.022 × 10²³. Use the ×10ⁿ button in the answer template or type 6.022*10^23.

Symbolic Answers: Show Every Multiplication

When the answer is an expression rather than a number, Mastering checks whether your expression is algebraically equivalent to the correct one, so you don't have to match the textbook's form exactly. The syntax still has to be unambiguous. Pearson's rules for entering symbolic answers include:

• Use * for multiplication and type 2*a*b, not 2ab. Do not use the letter x as a multiplication sign.
• Type a*(b+c), not a(b+c). Pearson's authoring guide explains that the second form means a is a function of b+c.
• Leave out spaces, and use commas only to separate multiple answers.
• After typing an exponent or a fraction in the template, move the cursor out of that box before continuing. Otherwise the rest of your expression ends up inside the exponent.

Degrees vs. Radians

Mastering reads trigonometric arguments as radians unless a question specifically asks for degrees. Pearson's own example accepts 10*cos(π/6) for an expression involving a 30° angle and rejects 10*cos(30), because cos(30) means the cosine of 30 radians. Convert the angle or use the π template.

Chemical Formulas and Equations

Chemistry entry has its own rules, listed in Pearson's guide to answering chemical equation questions:

• Write decimal coefficients as fractions, such as 1/2 O₂ rather than 0.5 O₂.
• Do not type spaces or periods.
• Capitalization matters, since co2 is not CO₂. Pearson's recommended feedback for this case is "Check the capitalization of the chemical symbols in your answer."
• Check phases and charges. Question authors can treat an unbalanced equation or a wrong phase, such as (s) where (aq) is required, as a penalized error.

Answers in a Required Order

Some parts ask for several values separated by commas, such as the x and y components of a vector. When the order is specified, Pearson notes that "Mastering uses string matching to grade such answers," so the right numbers in the wrong order are marked incorrect.

What Costs an Attempt and What Doesn't

By default, Mastering gives 6 attempts on most question parts and deducts 3% of the part's credit for each wrong answer that isn't multiple choice. Multiple-choice questions use a fractional penalty instead. Your instructor can change all of these settings. Within those rules, several kinds of mistakes are free:

Requesting the answer is the one move that always gives up the credit for that part. Pearson's confirmation message warns, "If you do, you will not get any credit for it."

MyLab Math and MyLab Statistics: Read the Instructions Under the Box

MyLab courses use a different answer player from Mastering, and their grading depends heavily on the short instruction printed under each answer box. Germanna Community College's student guide to MyLab Math notes that "the subtext often gives formatting and rounding instructions," with examples such as "Type an integer" and "Type fractions. Do not simplify." If the instructions say to round to two decimal places, 0.4167 is wrong even though it is more precise than 0.42.

Pearson's documentation for the MyLab player also shows that instructors choose how strictly answers are scored, including absolute or percentage tolerance and whether an equivalent but unsimplified answer earns credit. The default for unsimplified answers is no credit, so reduce fractions and simplify radicals unless the instructions say otherwise.

When you're stuck, the built-in tools help without costing you the question. View an Example walks through a similar problem, and Help Me Solve This guides you through the one in front of you. Answers you fill in during Help Me Solve This don't earn points, but afterward MyLab gives you a similar problem with new values that you can answer for credit. Our guide on getting help with Pearson homework explains how to use these tools well.

When It Isn't Your Answer: Technical Problems

Occasionally a correct answer doesn't register at all. Pearson documents a few causes worth ruling out:

• School network filters. Pearson notes that "in rare cases, educational networks identify students' Mastering answers as insecure communications" and block them. Try a different network to test this.
• Pop-up blockers. Some Pearson windows won't open properly with a pop-up blocker enabled.
• Browser problems. Clear the cache, update the browser, or try another one before assuming your work is wrong.

Pearson records every submitted answer in the gradebook with a date and time, so if a problem is technical, your instructor can usually see what you submitted.

A Checklist Before You Press Submit

1. Did you keep full precision until the last step?
2. Did you round to the significant figures or decimal places the question asks for?
3. Is the unit included, abbreviated, correctly capitalized, and in the right system?
4. Is scientific notation entered with ×10ⁿ, never e or E?
5. Is every multiplication written with *, and every function argument in parentheses?
6. Are angles in radians unless the question says degrees?
7. For chemistry, are coefficients whole numbers or fractions, symbols capitalized, and phases included?
8. For multiple values, are they in the order the question lists?

What to Do When You Still Think Mastering Is Wrong

Question banks do contain occasional errors. If you've worked a problem twice, checked every item on the list above, and still believe your answer is right, take a screenshot that shows the question, your answer and the feedback. Then email your instructor with your full working. Instructors can review the submission, adjust tolerance or credit for a specific item, and report a faulty question to Pearson. Polite, specific messages with your work attached get the quickest response.

If chemistry or physics homework keeps costing you points, working through problems with a tutor can help you spot the pattern in your mistakes. Our chemistry homework help and physics homework help connect you with subject experts who explain each step. Use any outside help in line with your school's academic integrity policy.

Frequently Asked Questions

Does Mastering Chemistry Grade Significant Figures?

Not directly. Mastering checks whether your value falls inside the grading tolerance, usually 2%. A differently rounded answer inside the band gets full credit with a note about rounding. An answer just outside it may get "Very close" feedback without a penalty.

What Is the Grading Tolerance in Mastering Physics?

The default is 2.00%, and most numeric questions use 2% or 3%. Questions requiring four significant figures often use a tolerance below 1%, and instructors can change the setting.

Why Does Mastering Say My Answer Is Wrong When I Used Scientific Notation?

You probably typed e or E. Mastering reads e as the constant 2.718, so 1.23e5 is not read as 1.23 × 10⁵. Enter 1.23*10^5 or use the ×10ⁿ button.

Do Wrong Units Cost an Attempt in Mastering?

It depends. A unit Mastering doesn't recognize doesn't cost an attempt, but a recognized wrong unit does, as does using a different unit system from the one the question specifies.

How Many Attempts Do You Get in Mastering?

The default is 6 attempts per part, with a 3% deduction for each wrong answer on most question types. Your instructor can change both settings, so check your course's grading policy.

Does Requesting the Answer in Mastering Lose All Points?

Yes, for that part of the question. Pearson warns that if you request the answer, "you will not get any credit for it."