Third Grade English: Foundational Reading & Phonics - Common Prefixes and Suffixes

Prefixes and suffixes are powerful word parts known as affixes that attach to base words to change their meanings, functions, or grammatical forms. By mastering common prefixes such as un-, re-, dis-, and pre-, as well as frequent suffixes including -ful, -less, -able, and -ly, you can unlock the definitions of thousands of unfamiliar words without opening a dictionary. Understanding how prefixes alter the direction or truth of a word, and how suffixes transform nouns, verbs, and adjectives, gives you an essential set of decoding tools for third grade reading.

Understanding Word Anatomy

Every complex English word is built from smaller building blocks. When you learn how these pieces lock together, reading long words becomes like assembling a puzzle.

+-------------------+--------------------+--------------------+
|      PREFIX       |     BASE WORD      |       SUFFIX       |
+-------------------+--------------------+--------------------+
| Added to FRONT    | Core word meaning  | Added to END       |
| Example: "re-"    | Example: "play"    | Example: "-able"   |
| Meaning: "again"  | Meaning: engage    | Meaning: capable of|
+-------------------+--------------------+--------------------+
|               FULL WORD: replayable                         |
|               Meaning: able to be played again              |
+-------------------------------------------------------------+

What Is a Base Word?

A base word, sometimes called a root word, is a standalone word that makes sense all on its own. For instance, the word "kind" is a base word. You can add the prefix "un-" to make "unkind," or you can add the suffix "-ness" to make "kindness." You can even add both to make "unkindness."

What Is a Prefix?

A prefix is a letter or group of letters attached to the beginning of a base word. Prefixes never stand alone as complete words in a sentence; their entire job is to modify or change the meaning of the base word that follows them.

What Is a Suffix?

A suffix is a letter or group of letters attached to the end of a base word. While a prefix changes the meaning of a word, a suffix frequently changes both the meaning and the part of speech. For example, adding "-ful" turns the noun "peace" into the adjective "peaceful."

Essential Third Grade Prefixes

In third grade, four prefixes appear more frequently than any others: un-, re-, dis-, and mis-. Memorizing their meanings will help you instantly decipher hundreds of new words.

+----------+--------------------+---------------------+--------------------+
|  PREFIX  |      MEANING       |     BASE WORD       |   NEW MEANING      |
+----------+--------------------+---------------------+--------------------+
| un-      | not, opposite of   | happy -> unhappy    | not happy          |
| re-      | again, back        | build -> rebuild    | build again        |
| dis-     | not, opposite of   | agree -> disagree   | not agree          |
| mis-     | wrong, badly       | lead  -> mislead    | lead wrongly       |
| pre-     | before             | view  -> preview    | view before        |
| non-     | not, without       | sense -> nonsense   | without sense      |
| im-/in-  | not, opposite of   | polite-> impolite   | not polite         |
+----------+--------------------+---------------------+--------------------+

The Prefix "un-" (Not / Opposite)

The prefix "un-" is one of the most common prefixes in English. It reverses the meaning of the base word.
- unlock: to undo a lock

- unwrap: to remove a wrapper

- uncertain: not certain or sure


The Prefix "re-" (Again / Back)

The prefix "re-" tells you an action is being repeated or returned to a previous state.
- rewrite: to write a text a second time

- refill: to fill a cup or container again

- return: to go back to a starting location


The Prefix "dis-" (Not / Opposite)

Like "un-", "dis-" turns a word into its opposite or expresses separation.
- disappear: to vanish from sight

- dislike: to not like something

- disobey: to refuse to obey directions


The Prefix "mis-" (Badly / Wrongly)

When you see "mis-", think of an error, mistake, or incorrect action.
- misspell: to spell a word incorrectly

- misunderstand: to fail to understand correctly

- misplace: to place an item in the wrong spot


Essential Third Grade Suffixes

Suffixes tell you what kind of word you are reading and how it functions inside a sentence.

+----------+---------------------+---------------------+-------------------+
|  SUFFIX  |       MEANING       |      BASE WORD      |    NEW MEANING    |
+----------+---------------------+---------------------+-------------------+
| -ful     | full of             | joy   -> joyful     | full of joy       |
| -less    | without, lacking    | fear  -> fearless   | without fear      |
| -able    | capable of, able to | wash  -> washable   | able to be washed |
| -ly      | in a certain manner | quick -> quickly    | in a quick manner |
| -er/-or  | one who does action | teach -> teacher    | one who teaches   |
| -ness    | state or quality of | dark  -> darkness   | state of dark     |
+----------+---------------------+---------------------+-------------------+

The Suffixes "-ful" and "-less"

These two suffixes form natural opposites:
- Careful: full of care and attention.

- Careless: without care or attention.

- Helpful: full of help; ready to assist.

- Helpless: lacking help; unable to act alone.


The Suffix "-ly" (Adverbs of Manner)

Adding "-ly" to an adjective turns it into an adverb describing how an action takes place.
- slow + ly = slowly (The turtle walked slowly.)

- quiet + ly = quietly (She closed the bedroom door quietly.)

- cheerful + ly = cheerfully (They sang cheerfully in the morning.)


The Suffixes "-er" and "-or" (Agent Nouns)

These suffixes identify a person or thing that performs a specific action.
- write + er = writer (a person who writes stories)

- sail + or = sailor (a person who sails ships)

- paint + er = painter (a person who paints walls or artwork)


Spelling Rules When Adding Suffixes

Sometimes you cannot simply attach a suffix without adjusting the base word. Three golden spelling rules govern these changes: the Double Consonant Rule, the Drop the Silent E Rule, and the Change Y to I Rule.

+-------------------------------------------------------------+
|               THREE SUFFIX SPELLING RULES                   |
+-------------------------------------------------------------+
|  1. DROP SILENT E: make + ing = making                      |
|  2. DOUBLE CONSONANT (1-1-1 Rule): run + ing = running      |
|  3. CHANGE Y TO I: happy + ness = happiness                 |
+-------------------------------------------------------------+

Rule 1: Drop Silent E

When a base word ends with a silent 'e' and you add a suffix that starts with a vowel (such as -ing, -ed, -able), drop the 'e' before attaching the suffix.
- bake + ing = baking (drop the e)

- hope + ed = hoped (drop the e)

- love + able = lovable (drop the e)


Rule 2: The 1-1-1 Doubling Rule

When a one-syllable base word ends with 1 vowel followed by 1 consonant, double the final consonant before adding a suffix starting with a vowel.
- hop + ing = hopping (double the p so it does not say hoping)

- sit + er = sitter (double the t)

- big + est = biggest (double the g)


Rule 3: Change Y to I

When a base word ends in a consonant plus 'y', change the 'y' to an 'i' before adding most suffixes (except suffixes beginning with 'i', such as -ing).
- carry + ed = carried

- beauty + ful = beautiful

- dry + ing = drying (keep the y before -ing)


Step-by-Step Word Decoding Strategy

Follow this four-step checklist whenever you meet an intimidating multisyllable word in your reading.

+-------------------------------------------------------------+
|                 FOUR-STEP DECODING PROCESS                  |
+-------------------------------------------------------------+
|  Step 1: Look for a prefix at the front. Box it.            |
|  Step 2: Look for a suffix at the back. Underline it.       |
|  Step 3: Read the base word left in the middle.             |
|  Step 4: Blend all parts together and state the meaning.   |
+-------------------------------------------------------------+

Guided Example: "Uncomfortable"

  1. Identify prefix: "un-" (means not).
  2. Identify suffix: "-able" (means capable of).
  3. Identify base word: "comfort" (state of physical ease).
  4. Put it together: "un-" + "comfort" + "able" = not capable of providing comfort.

Guided Practice and Review

Work through these practice exercises to test your understanding of prefixes and suffixes.

Exercise 1: Identify the Word Parts

Break each word into its prefix, base word, and suffix.
1. Replayable

2. Disrespectful

3. Unhealthy


Exercise 2: Create New Words

Apply the correct spelling rules to combine the words below.
1. write + ing

2. sun + y

3. worry + ed


Exercise 3: Context Sentence Completion

Select the correct affix word for each blank.
1. Because the instructions were confusing, Oliver had to _ the puzzle. (redo / undo)

2. The flashlight was completely _ without fresh batteries. (useful / useless)


Answer Key and Explanations

  • Exercise 1:
  • Replayable = Prefix "re-", base word "play", suffix "-able".
  • Disrespectful = Prefix "dis-", base word "respect", suffix "-ful".
  • Unhealthy = Prefix "un-", base word "health", suffix "-y".
  • Exercise 2:
  • writing (Drop the silent e before -ing).
  • sunny (Double the consonant n after short u).
  • worried (Change consonant + y to i before -ed).
  • Exercise 3:
  • redo (To do again).
  • useless (Lacking use or function).