In this Grade 3 vocabulary lesson from Vocabulary from Classical Roots (Book 5), students learn how the prefixes in- and semi- change the meaning of base words, building words such as inactive, insignificant, semiannual, and semiconscious. Exercises guide students through matching prefix clues to meanings, identifying synonyms, and using context to fill in blanks with vocabulary words. The lesson also extends learning by exploring related negative prefixes — ig-, il-, im-, and ir- — and comparing them to un-, dis-, and non-.
Section 1
The Prefix 'in-': Meaning Not
The prefix in- is a game-changer! It flips the meaning of a word to its opposite, usually meaning 'not.' Let's look at how this works.
| Word | Definition |
|---|---|
| inactive | (adj.) not active; not moving or in use |
| informal | (adj.) casual; not formal |
| insignificant | (adj.) not important; too small to matter |
| insomnia | (n.) the condition of being unable to sleep |
Section 2
The Prefix 'semi-': Meaning Half or Partly
When you see the prefix semi-, think 'half' or 'partly.' It describes something that is incomplete or happens midway. Here are some words that use it.
| Word | Definition |
|---|---|
| semiannual | (adj.) happening twice a year |
| semiconscious | (adj.) only partly awake or aware |
| semicolon | (n.) a punctuation mark (;) that shows a pause longer than a comma but shorter than a period |
| semiformal | (adj.) partly formal; dressier than casual but not fully formal |
| semiprecious | (adj.) valuable but not as rare or expensive as precious stones |
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Section 1
The Prefix 'in-': Meaning Not
The prefix in- is a game-changer! It flips the meaning of a word to its opposite, usually meaning 'not.' Let's look at how this works.
| Word | Definition |
|---|---|
| inactive | (adj.) not active; not moving or in use |
| informal | (adj.) casual; not formal |
| insignificant | (adj.) not important; too small to matter |
| insomnia | (n.) the condition of being unable to sleep |
Section 2
The Prefix 'semi-': Meaning Half or Partly
When you see the prefix semi-, think 'half' or 'partly.' It describes something that is incomplete or happens midway. Here are some words that use it.
| Word | Definition |
|---|---|
| semiannual | (adj.) happening twice a year |
| semiconscious | (adj.) only partly awake or aware |
| semicolon | (n.) a punctuation mark (;) that shows a pause longer than a comma but shorter than a period |
| semiformal | (adj.) partly formal; dressier than casual but not fully formal |
| semiprecious | (adj.) valuable but not as rare or expensive as precious stones |
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter