Introduction: Your Vocabulary "Decoder Ring"

Have you ever come across a long, scary-looking word in an English text and felt like giving up? Don't worry! Most long words in English are actually made of smaller pieces put together like LEGO bricks. In this chapter, we will learn about Word Formation and Parts of Speech. By understanding how words are built, you can "decode" the meaning of thousands of new words without even looking at a dictionary! This is a vital skill for reaching the B1 level required for ม.6 graduation.

Quick Note: This chapter focuses on how words change shape. For how words naturally hang out together, check out our chapter on "Collocations and fixed expressions."

1. The "Big Four" Parts of Speech

To build words, we first need to know the four main categories. Think of these as the roles players have on a football team:

  • Nouns (Names): These are people, places, things, or ideas. (Examples: student, school, happiness, environment)
  • Verbs (Actions): These are what you do or what happens. (Examples: study, eat, develop, succeed)
  • Adjectives (Descriptions): these describe nouns. (Examples: smart, green, beautiful, scientific)
  • Adverbs (Details): These describe how an action is done. They usually end in -ly. (Examples: quickly, slowly, happily, successfully)

Key Takeaway: Before you can change a word, you must identify its current job in the sentence!

2. Building Words with Prefixes

A prefix is a group of letters added to the beginning of a word. Prefixes usually change the meaning of the word, but keep it in the same Part of Speech.

Common Prefixes to Remember:

To say "No" or "Opposite" (Negatives):

  • un- : happy \(\implies\) unhappy
  • dis- : agree \(\implies\) disagree
  • im- / in- / ir- : possible \(\implies\) impossible; regular \(\implies\) irregular

To show "Again":

  • re- : write \(\implies\) rewrite; cycle \(\implies\) recycle

To show "Wrongly":

  • mis- : understand \(\implies\) misunderstand

Did you know? Using prefixes like re- and un- is a very common way to talk about Environment (e.g., reusable, unkind to nature) and Science & Technology (e.g., disconnect, research), which are key topics in your syllabus!

3. Changing Categories with Suffixes

A suffix is a group of letters added to the end of a word. Suffixes usually change the Part of Speech (e.g., turning a verb into a noun).

Suffixes that make NOUNS:

  • -tion / -sion: pollute (v) \(\implies\) pollution (n)
  • -er / -or (people): teach (v) \(\implies\) teacher (n)
  • -ness: weak (adj) \(\implies\) weakness (n)
  • -ment: develop (v) \(\implies\) development (n)

Suffixes that make ADJECTIVES:

  • -ful: care (n) \(\implies\) careful (adj)
  • -less (without): care (n) \(\implies\) careless (adj)
  • -able / -ible: use (v) \(\implies\) usable (adj)
  • -ive: create (v) \(\implies\) creative (adj)

Suffixes that make ADVERBS:

  • -ly: quick (adj) \(\implies\) quickly (adv)

Memory Trick: Think of the suffix -less as "minus." If someone is fearless, they are "fear minus" — they have no fear!

4. Word Families: Seeing the Whole Picture

In your exams, you might be asked to complete a sentence with the correct form of a word. We call these Word Families. Let's look at a family for the word "Success":

  • Verb: to succeed (I want to succeed in my career.)
  • Noun: success (Hard work leads to success.)
  • Adjective: successful (She is a successful doctor.)
  • Adverb: successfully (He successfully finished the race.)

Quick Tip: If the word comes after "a", "an", or "the", it is likely a Noun. If it comes before a noun, it is likely an Adjective!

5. Strategies for Exams (Context Clues)

The syllabus requires you to use context clues to guess the meaning of words. Here is how to do it step-by-step:

Step 1: Look at the neighbors. Look at the words before and after the unknown word. Are there clues about its Part of Speech?

Step 2: Break it down. Do you see a prefix or suffix you recognize? (e.g., if you see -ment, you know it's a "thing" or "result").

Step 3: Check the tone. Is the sentence talking about something good or bad? A prefix like mis- or dis- tells you the meaning is likely negative.

Summary & Key Takeaways

Don't worry if this seems tricky at first! Word formation is like a puzzle. The more you practice, the more patterns you will see.

Key Points to Remember:
1. Nouns, Verbs, Adjectives, and Adverbs are the four main word roles.
2. Prefixes (at the start) change meaning (e.g., un-, re-, dis-).
3. Suffixes (at the end) change the Part of Speech (e.g., -tion, -ly, -ful).
4. Use Context Clues to guess meanings in reading passages about topics like Travel, Health, and Science.

Quick Review Box

What is the noun form of "imagine"? (Answer: imagination)
What does "reappear" mean? (Answer: to appear again)
Which suffix makes the adjective "beauty" into an adverb? (Answer: -fully \(\implies\) beautifully)