Grade by Grade
B. Foundations of Language · Cursive, Spelling and Sentences

Prefixes, Bases and Word Families

B2.3 B2.4About 40 minutes
Learning goals
  • I can add prefixes like un-, re-, dis-, mis-, pre-, non-, over- and in- and tell how they change a word's meaning.
  • I can use number prefixes bi- (two) and tri- (three).
  • I can spell a word with a prefix without changing the spelling of the base.
  • I can build a word family from one base, like help, helper, helpful, unhelpful.

Words to know

prefix
A word part added to the beginning of a base, like re- in reread.
base
The main part of a word that carries its meaning.
word family
A group of words that share the same base, like play, player, playful, replay.
morpheme
The smallest part of a word that has meaning.

A word puzzle

What does unbreakable mean? You might never have seen it before, but you can figure it out!

  • un- means not
  • break is the base
  • -able means can be

So unbreakable means cannot be broken. Knowing word parts is like having a secret decoder!

unbreakableun + break + able = unbreakable
Prefix + base + suffix

Remember from Grade 2

You learned the prefixes un- (not), re- (again), dis- (not, or the opposite of), mis- (wrongly) and pre- (before). In Grade 3, here are some new ones.

PrefixMeaningExamples
un-not, or the opposite ofunhappy, unlock, unfair
re-again, or backreread, rebuild, return
dis-not, or the opposite ofdislike, disagree, disappear
mis-wronglymisspell, misread, misplace
pre-beforepreheat, preview, preschool
non-notnonstop, nonfiction, nonsense
over-too much, or aboveoverflow, overeat, overhead
in-notincorrect, incomplete, invisible
bi-twobicycle, bilingual (speaking two languages)
tri-threetriangle, tricycle
Prefixes and their meanings

Is it really a prefix?

Watch out: not every word that starts with these letters has a prefix! In uncle, ready and dish, the letters un, re and dis are just part of the word. Test it: take the letters off. Is a real base left that makes sense? un + cle? No, so uncle has no prefix.

Just for fun

If un- means not, is your uncle someone who is not a cle? Nope! Always test it: un + cle doesn't leave a real base word.

Prefixes don't change the base's spelling

This makes prefixes easy to spell. Just write the prefix, then the whole base:

  • mis + spell = misspell (two s's: one from mis, one from spell)
  • un + natural = unnatural (two n's)
  • dis + satisfied = dissatisfied (two s's)
  • over + run = overrun (two r's)

If the prefix ends with the same letter the base starts with, you get a double letter. That's correct!

mis+spell=misspellun+natural=unnaturaldis+satisfied=dissatisfiedover+run=overrunKeep every letter! The prefix and the base never change their spelling.
When a prefix ends with the same letter the base starts with, you get a double letter, and that is correct.
Worked example

Let's build "misspell"

Spell the word that means to spell wrongly.

  1. wrongly = mis-. The base is spell.
  2. Write the prefix: mis. Then the whole base: spell.
  3. Don't drop a letter: mis + spell = misspell.

misspell, with two s's

Worked example

Let's figure out "nonfiction"

What does nonfiction mean?

  1. Break it into parts: non + fiction.
  2. non- means not. fiction means made-up stories.
  3. So nonfiction means not made up: books with true facts.

nonfiction = books that give true information

Word families

One base can grow a whole family of words. Adding prefixes and suffixes changes the meaning, but the base keeps its spelling. This helps you spell long words!

BaseFamily members
helphelper, helpful, helpless, unhelpful, helping
playplayer, playful, replay, playground
agreeagreement, disagree, disagreement, agreeable
cyclebicycle, tricycle, recycle
viewpreview, review, viewer
Word families
Worked example

Let's grow a word family

Make as many words as you can from the base kind.

  1. Add suffixes: kindness, kindly.
  2. Add a prefix: unkind.
  3. Add both: unkindness, unkindly.
  4. Check: kind is spelled the same way in every word.

kind, kindly, kindness, unkind, unkindly, unkindness

Hands-on activity

Prefix flip book

You need: 2 strips of paper, a stapler or tape, and a marker.

  1. On the first strip, write prefixes on small flaps: un, re, dis, pre, mis, non, over.
  2. On the second strip, write bases: pack, fill, like, heat, read, stop, sleep.
  3. Line up the flaps so a prefix sits next to a base. Read the word. Is it a real word? (refill yes, nonheat no.)
  4. For each real word, tell a grown-up what it means: "oversleep means to sleep too much."
  5. Write 3 of your real words in sentences, like: I had to repack my bag for the trip to Grandma's.

Your turn

1

What does reheat mean?

2

Add a prefix to agree to make its opposite.

3

What does incorrect mean?

4

Spell the word that means to place wrongly.

5

How many wheels does a tricycle have? How do you know?

6

Which word has a prefix: uncle or unlock?

7

Write three words in the play word family.

More practice: warm-up

1

What does unhappy mean?

2

Find the prefix in preheat.

3

What does nonstop mean?

4

Add re- to build.

5

How many wheels does a bicycle have?

More practice: on your own

1

Spell un + natural. How many n's are in the middle?

2

What does overflow mean? Use it in a sentence.

3

Write a word sum for disagreement.

4

Is invisible something you can see? How do you know?

5

Make a word family from care. Write four words.

Challenge

1

What does unbreakable mean? Show the word parts.

2

Your friend wrote mispell. Explain the mistake.

3

Make up a word using a prefix and a base that isn't in a dictionary yet, and tell what it would mean. (Example: unsnowy)

Check your understanding

Quiz

1.

What does the prefix re- mean?

2.

Which word means heat before?

3.

Which is spelled correctly?

4.

What does nonfiction mean?

5.

Which word does not have a prefix?

6.

Which word belongs to the help word family?

For parents and teachers

Big idea: Grade 3 students use knowledge of bases, prefixes and suffixes to read and spell words (B2.3), and this builds vocabulary (B2.4). A child who knows that in- means not can work out incomplete, incorrect and invisible without being taught each one.

How to help at home:

  • Play "word part detective" with signs and packaging: preheat, nonstick, refillable, unsalted.
  • Grow word families on a sheet of paper over a week.
  • When your child meets a new long word, cover the prefix and suffix so they see the base first.

Common difficulties:

  • Dropping a double letter (mispell, unatural). Write the prefix, then the whole base.
  • False prefixes (uncle, ready, dish). Test by removing the letters: is there a real base that matches the meaning?
  • in- doesn't always mean not (inside, into). Discuss the meaning in context.