🎯 Master Word Forms to Win TOEIC Part 5

If TOEIC grammar questions feel tricky — especially when all the options look like the same word — you're facing one of the most common traps in the test: word form confusion.

These questions aren’t about whether you know the word.
They’re about whether you know which version of the word fits.

Let’s fix that right now.

🧠 What Is a Word Family?

A word family is a group of related words built from the same base, but with different endings. They often include a noun, verb, adjective, and adverb.

For example:

  • success (noun)

  • succeed (verb)

  • successful (adjective)

  • successfully (adverb)

The meanings are related, but the grammar roles are different. And TOEIC loves to test these differences — especially in Part 5.

❌ Why Learners Get These Wrong

Many TOEIC test-takers try to understand each sentence by vocabulary meaning alone.
But Part 5 questions often give you four words that all “look right” — unless you understand grammar roles.

Consider this:

The company’s recent ______ led to a major contract.

Choices:

  • succeed

  • successful

  • success

  • successfully

The only grammatically correct answer is “success” — the noun.
Why? Because the blank needs a noun to follow “recent,” and only “success” fits.

You didn’t need to translate. You needed to recognize the function of the word.

🔍 How TOEIC Tests Word Form Confusion

TOEIC Part 5 questions often follow these patterns:

  • A blank after a preposition like “of,” “with,” or “by” — usually requires a noun.

  • A blank before a noun — usually needs an adjective.

  • A blank after “to” — usually needs a verb.

  • A blank between the subject and the verb — often an adverb.

The options will all look like good vocabulary words, but only one fits the sentence structure.

📚 Examples of High-Frequency Word Families

Here are some word families that show up again and again in TOEIC:

  • apply / application / applicable

  • decide / decision / decisive / decisively

  • approve / approval / approving

  • perform / performance

  • compete / competition / competitive / competitively

  • manage / management / managerial / manager

You don’t need to memorize these — you need to recognize them in context.

📝 Sample TOEIC Question

The board was impressed with the applicant’s ______.

A) decide
B) decision
C) decisive
D) decisively

Correct answer: decision

Why? The blank comes after a preposition (“with”), so it needs a noun. “Decision” is the noun. The others are grammatically incorrect here.

This is typical of how TOEIC hides a grammar test inside a vocabulary test.

✅ How to Train This Skill

Here’s how to improve — fast:

  1. Spot the signal. Look at what comes before and after the blank.

  2. Label the role. Is it a subject? An object? An adjective before a noun? A verb after “to”?

  3. Eliminate the wrong forms. If the sentence needs a noun, cross out any verbs or adjectives.

  4. Test the sentence. Read it out loud with the correct word. Does it flow naturally?

The key is to train your eyes to see not just words, but word roles.

📈 Why This Topic Is a TOEIC Favourite

Because it checks two things at once:

  • Your grammar awareness under pressure

  • Your ability to understand business English structure

Word family questions appear in almost every TOEIC test. They're fast to answer — but only if you’ve trained your instinct.

🚀 Final Tip: Don't Study Vocabulary — Study Grammar in Context

Instead of memorizing lists, focus on how word forms are used in real sentences.
TOEIC Part 5 isn’t testing if you know the word — it’s testing if you can choose the right form based on grammar structure.

Train your eye to spot roles, not just meanings.
That’s how you improve speed, accuracy, and score.

Q1: What’s the difference between “success” and “successful”? A1: “Success” is a noun. “Successful” is an adjective. Example: She had great success. ✅ (noun) She is a successful person. ✅ (adjective) Q2: How do I know when to use a noun vs a verb? A2: Look at the grammar around the blank. After “the” or “a,” you usually need a noun. After “to,” you usually need a verb. Q3: What part of speech usually comes after a preposition like “with” or “by”? A3: A noun. Example: He was praised by the manager. → “manager” is a noun. Q4: What’s the trick to solving word family questions in Part 5? A4: Don’t guess based on word meaning. Look at the sentence structure. Eliminate options that don’t match the grammar role (verb, noun, etc). Q5: Is “decide” a noun or a verb? A5: “Decide” is a verb. The noun form is “decision.” Example: They will decide tomorrow. ✅ It was a difficult decision. ✅ Q6: What’s the adverb form of “successful”? A6: “Successfully.” Example: She successfully launched the product. Q7: Are word families common in TOEIC Part 5? A7: Yes — they appear in almost every test. TOEIC often gives you four options from the same family and tests your grammar knowledge, not just vocabulary. Q8: Can I just memorize which form is right? A8: Not reliably. TOEIC changes the sentence. You need to understand why a noun or verb fits based on the sentence pattern. Q9: What if two options seem possible? A9: Double-check what comes before and after the blank. That will tell you what part of speech is needed. Q10: Is it better to learn word families as groups? A10: Yes. Instead of learning words one by one, group them by form — verb, noun, adjective, adverb — and practice switching between them in full sentences.