Identify the line of text that contains an error in word or...

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Why Finding Errors Matters

People have cared about using words correctly for thousands of years. In ancient Greece and Rome, teachers called grammarians (experts in language rules) taught students how to speak and write clearly. They believed that using the right words showed that you could think clearly too.

Over time, people created dictionaries and grammar books to record the "correct" way to use words. Today, standardized tests like the TACHS (Test for Admission into Catholic High Schools) check whether you can spot errors in writing. This skill helps you become a better writer and reader.

~400 BCE

Ancient Grammar Studies

Greek scholars began writing down rules for clear communication, creating early grammar guides.

1755

Johnson's Dictionary

Samuel Johnson published one of the first major English dictionaries, helping standardize word usage.

1800s

Grammar in Schools

American schools began teaching formal grammar rules. Students practiced identifying errors in sentences.

1900s–Today

Standardized Testing

Tests like the TACHS began using error-identification questions to measure students' knowledge of Standard English.

So how do you actually find an error hiding in a sentence? That is the question we will answer in this lesson. You will learn the most common types of mistakes and a step-by-step method for catching them.

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Core Principles of Error Identification

On the TACHS, you will see a short passage broken into numbered lines. Your job is to find the line that contains a mistake in word usage (choosing the wrong word) or sentence usage (building a sentence incorrectly). Sometimes there is no error at all. Let's look at the main ideas behind this skill.

Word Choice Errors

Using the wrong word — like writing "their" when you mean "there," or "accept" when you mean "except." These are called homophones (words that sound alike but mean different things) or confused words.

Subject-Verb Agreement

The subject and verb must match in number. A singular subject needs a singular verb. For example, "The dogs runs fast" is wrong because "dogs" is plural but "runs" is singular.

Verb Tense Errors

Verbs must stay in a consistent tense (past, present, or future). Switching tenses without reason — like "She walked to school and opens her locker" — is an error.

Pronoun Errors

Pronouns (he, she, them, it) must clearly match the noun they replace. "Each student should bring their own pencil" mixes singular "each" with plural "their."

No Error Option

Sometimes every line is correct. Do not force yourself to pick an error if none exists. Check each line carefully and choose "No error" when everything looks right.

✦ KEY TAKEAWAY

Think of error identification like being a detective. You are searching for the one "suspect" line that breaks the rules of Standard English. Read every line like you are checking clues — slowly and carefully. If no line is guilty, then the answer is "No error."

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Visualizing the Error-Finding Process

The diagram below shows the step-by-step process you should follow when you see an error-identification question on the TACHS. Start at the top and move down through each check. This flowchart will help you build a habit of reading carefully.

Follow these four checks in order for every question: word choice, subject-verb agreement, verb tense, and pronoun agreement. If nothing is wrong, choose "No error."

Notice that the flowchart has four checkpoints. You do not need to memorize fancy grammar terms. Just ask yourself four simple questions at each line: Is the right word used? Do the subject and verb match? Are the verb tenses consistent? Do the pronouns match what they refer to? That is all it takes.

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How Common Errors Work

Commonly Confused Words

Many TACHS questions test commonly confused words. These are pairs or groups of words that sound similar but have different meanings. Here are some of the most important ones to know.

Commonly Confused Word Pairs

Word	Meaning	Example
their	belonging to them	Their dog is friendly.
there	a place, or used to introduce	There is the library.
they're	they are	They're going to the park.
your	belonging to you	Your backpack is open.
you're	you are	You're doing great.
accept	to receive or agree to	I accept the award.
except	not including	Everyone except Maria left.
affect	to influence (verb)	Rain will affect the game.
effect	a result (noun)	The effect was amazing.

Subject-Verb Agreement Rules

A singular subject takes a singular verb, and a plural subject takes a plural verb. A tricky part is when extra words come between the subject and verb. For example: "The box of chocolates is on the table." The subject is "box" (singular), not "chocolates." So "is" is correct.

Verb Tense Consistency

When a passage is written in the past tense, all verbs should stay in the past tense unless there is a good reason to switch. For instance, "She walked to the store and buys some apples" incorrectly shifts from past ("walked") to present ("buys"). It should say "bought."

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Classifying the Most Common Error Types

The diagram below organizes the error types you are most likely to see on the TACHS. Think of it as a quick-reference guide. Each branch shows a different category of mistakes along with an example.

This chart groups the four major error types you will encounter. The memory tricks at the bottom give you a quick question to ask yourself for each type.

💡 Test-Day Tip

Read each line on its own first. Then read it in the context of the whole passage. An error that hides when you read quickly often shows itself when you slow down and focus on one line at a time.

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Worked Example: Finding the Error

Let's walk through a sample TACHS-style question together. Read the passage below, which is split into four lines.

📝 Sample Passage

(Line 1) The science fair projects were displayed in the gymnasium. (Line 2) Each student explained there experiment to the judges. (Line 3) The judges asked thoughtful questions about every project. (Line 4) At the end, the principal announced the winners.

Step-by-Step Error Search

Step 1 — Read the Full PassageRead all four lines from start to finish to get the overall meaning. The passage is about a science fair. It uses the past tense throughout ("were displayed," "explained," "asked," "announced"). So far, the tense seems consistent.

Step 2 — Check Word Choice in Each LineLine 1: "displayed in the gymnasium" — all words are correct. Line 2: "explained there experiment" — wait! "There" means a place. The sentence needs "their," which means "belonging to them." This is a word choice error.

Error found on Line 2: "there" should be "their."

Step 3 — Confirm by Checking the Other LinesLine 3: "The judges asked thoughtful questions" — subject "judges" (plural) matches "asked" (plural). Good. Line 4: "the principal announced the winners" — correct word usage and agreement. No errors in Lines 3 or 4.

Step 4 — Select Your AnswerBecause Line 2 contains the word choice error ("there" instead of "their"), you would select Line 2 as your answer.

Answer: Line 2

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Strengths and Pitfalls of Different Strategies

There are different ways students try to find errors on the TACHS. Some strategies work better than others. The table below compares three common approaches so you can pick the one that works best for you.

Comparing Error-Finding Strategies

Strategy	Strengths	Pitfalls
Read aloud in your head	Helps you "hear" errors that look normal on paper. Good for catching awkward phrasing.	Can be slow. Some errors (like their/there) sound the same, so you might miss them.
Line-by-line checklist	Systematic and thorough. You check every category of error for every line. Least likely to miss something.	Takes more time. Requires you to remember the checklist. Needs practice to become fast.
Jump to the line that "feels wrong"	Very fast. Experienced readers often spot errors by instinct.	Risky if you are guessing based on feelings. May skip the real error or choose a correct line.

✦ KEY TAKEAWAY

Think of the line-by-line checklist like a recipe. A good cook follows the recipe step by step instead of just guessing how much salt to add. On the TACHS, the checklist approach is your recipe for finding errors. It may feel slow at first, but with practice it becomes second nature.

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Connecting to Advanced Writing Skills

The error-identification skill you are learning now is not just for the TACHS. It is a stepping stone to more advanced writing and editing skills. In high school and college, you will move from spotting errors to revising (improving sentences for clarity) and editing (polishing grammar, spelling, and style). The table below shows how the skills build on each other.

How Error Identification Leads to Advanced Skills

Skill Level	What You Do	Example
Identify Errors (Now)	Find the line with a mistake in word or sentence usage.	Spot "there" when it should be "their."
Correct Errors (Next)	Not only find the mistake but choose the correct replacement.	Replace "there" with "their" in the sentence.
Revise & Edit (Advanced)	Improve sentences for clarity, flow, and style — even if there is no "error."	Rewrite a correct but clunky sentence to make it clearer and more engaging.

By getting really good at spotting errors now, you are building a strong foundation. Every great writer is first a great editor. The more errors you can catch, the stronger your own writing will become.

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Practice Problems

Try these five practice problems. For each one, read the lines and decide which line contains an error in word or sentence usage. If no line has an error, choose "No error."

PROBLEM 1 — CONCEPTUAL

(Line 1) Maria likes to read books about history. (Line 2) She goes to the library every Saturday. (Line 3) Her favorite book is about the American Revolution. (Line 4) She has read it too times already. Which line contains an error?

PROBLEM 2 — BASIC

(Line 1) The team of players were excited about the tournament. (Line 2) They practiced every afternoon for two weeks. (Line 3) The coach gave each player a new uniform. (Line 4) Everyone felt ready to compete. Which line contains an error?

PROBLEM 3 — INTERMEDIATE

(Line 1) Last summer, we traveled to Washington, D.C. (Line 2) We visit the Lincoln Memorial and the Smithsonian. (Line 3) My favorite part was seeing the Declaration of Independence. (Line 4) We took hundreds of photos during the trip. Which line contains an error?

PROBLEM 4 — APPLIED

(Line 1) The school's new recycling program has been a great success. (Line 2) Students separate paper, plastic, and glass into different bins. (Line 3) The janitor collects the bins and takes them to the recycling center. (Line 4) Everyone in the school are proud of the program. Which line contains an error?

PROBLEM 5 — CRITICAL THINKING

(Line 1) The mayor announced that new parks would be built this year. (Line 2) The parks will include playgrounds, walking trails, and gardens. (Line 3) Neither the residents nor the mayor were surprised by the cost. (Line 4) The community accepted the plan with enthusiasm. Which line contains an error?

SUMMARY

Lesson Summary

To identify the line with an error on the TACHS, check for four main types of mistakes: word choice errors (like confusing "their," "there," and "they're"), subject-verb agreement errors (making sure the subject and verb match in number), verb tense inconsistencies (keeping past, present, or future tense consistent), and pronoun agreement errors (making sure pronouns match the nouns they replace).

Use a line-by-line checklist approach: read the full passage first, then go through each line checking for word choice, agreement, tense, and pronouns. If every line is correct, choose "No error". Remember, finding the true subject of a sentence — ignoring extra words between the subject and verb — is one of the most important tricks for getting these questions right.