Lesson 5: Smart Guessing: Using Word Parts & Context
Become a Word Detective
What do you do when you see a new word and you don't have a dictionary? Strong readers don't panic—they become detectives. They look for clues to guess the word's meaning. This lesson will teach you how to use the two most important clues: the word's internal structure (its parts) and the context of the sentence. Learning to infer3 the meaning of new words will make your reading faster and more effective.
Clue #1: The Word's Parts (Prefixes & Suffixes)
Many English words are built from smaller parts. If you know the parts, you can often make an excellent guess about the meaning.
- A Prefix1 is a group of letters at the beginning of a word that changes its meaning.
- A Suffix2 is a group of letters at the end of a word that often changes its part of speech (e.g., from a verb to a noun).
Common Prefixes:
| Prefix | Meaning | Example |
|---|---|---|
| un-, in-, im-, ir- | not, opposite of | unhappy, incorrect, impossible, irregular |
| re- | again, back | reread, rebuild, return |
| pre- | before | preview, pre-war, prehistoric |
Common Suffixes:
| Suffix | Function | Example |
|---|---|---|
| -tion, -sion | Makes a noun | information, decision |
| -able, -ible | Makes an adjective (means 'can be done') | readable, responsible |
| -ology | Makes a noun (means 'the study of') | biology, sociology |
Clue #2: The Context of the Sentence
The words and sentences around a new word give you powerful clues about its meaning. Ask yourself:
- Are there synonyms or antonyms? e.g., "He wasn't friendly; in fact, he seemed quite hostile." (Hostile must mean something like "unfriendly").
- Is there a cause and effect? e.g., "Because she practiced every day, her success was inevitable." (Inevitable must mean "certain to happen").
In Practice: A Detective at Work
Leakhena is reading an article about infrastructure in Cambodia. She sees this sentence: "Because the old bridge was unstable, the government decided to rebuild it."
- Word 1: unstable
She sees the prefix un- (not) and the word stable. She guesses "not stable" or "not strong." The context confirms this: because it was "not stable," it needed to be rebuilt. Her guess is correct. - Word 2: rebuild
She sees the prefix re- (again) and the word build. She guesses "to build again." The context confirms this perfectly.
Without a dictionary, Leakhena successfully understood two key words.
quiz Check Your Understanding
1. The prefix "re-" in a word like "review" means...
- a) not
- b) before
- c) again
Click to see the answer
Answer: c) again
2. In the sentence, "He was extremely tired after the **arduous** 10-hour hike up the mountain," the word "arduous" most likely means...
- a) easy and relaxing
- b) difficult and requiring a lot of effort
- c) short and quick
Click to see the answer
Answer: b) difficult and requiring a lot of effort (The context of a 10-hour hike tells you this).
3. The suffix "-able" in a word like "washable" means that something...
- a) ...cannot be washed.
- b) ...can be washed.
- c) ...is the study of washing.
Click to see the answer
Answer: b) ...can be washed.
edit Your Mission
- Prefix Power: The word "impossible" uses a prefix meaning "not". Can you think of one other word that uses "im-", "in-", "un-", or "ir-" to mean "not"? Write it down.
- Context Clues: Read the following sentence: "The temple was ancient, but the buildings surrounding it were all contemporary." Based on the context, what do you think "contemporary" means? (Hint: The word "but" is a big clue).
- The No-Dictionary Challenge: Find a short English article online. Read one paragraph and find a word you don't know. Try to be a detective: use its parts and the context to guess the meaning. Write down the word, your guess, and why you guessed it. Then, you can check your answer with a dictionary.
book Lesson Glossary
- Prefix (noun) - Khmer: បុព្វបទ - A group of letters added to the beginning of a word to change its meaning. ↩
- Suffix (noun) - Khmer: បច្ច័យ - A group of letters added to the end of a word to change its meaning or function. ↩
- To Infer (verb) - Khmer: សន្និដ្ឋាន - To form an opinion or guess that something is true because of the information that you have. ↩