Prefixes and suffixes
Build and unlock words like Lego: add a prefix or a suffix to a base word, and use the parts to work out what a new word means
About three lessons of 45 to 55 minutes
Build and unlock words like Lego
Words are built from parts, just like Lego. Start with a base such as happy, snap a piece on the front, and you get unhappy. Snap a different piece on the end and you get happiness. The same base word can be built into many words by adding parts.
Those parts have names. A prefix clicks onto the front, a suffix clicks onto the end, and both change what the word means. Learn the common ones and you can do two powerful things: build new words, and unlock the meaning of a long word you have never seen by breaking it back into parts.
- un + happy = unhappya prefix on the front flips the meaning to 'not happy'
- happy + ness = happinessa suffix on the end turns it into 'the state of being happy'
- re + build = rebuildre- means again, so rebuild means build again
- hope + less = hopelesssplit a long word into parts to unlock its meaning: without hope
What students will be able to do
Students will understand that many words are built from a base word plus a prefix or a suffix, will identify the base and the affix in a word, will know the meaning of common prefixes (un-, re-, pre-, dis-) and suffixes (-ful, -less, -ly, -ness), will combine the base meaning with the affix meaning to work out an unfamiliar word, and will apply the spelling changes needed when adding a suffix.
- I can split a word into its base word and its affix.
- I can name what common prefixes and suffixes mean.
- I can build a new word by adding a prefix or a suffix to a base word.
- I can work out an unfamiliar word's meaning by combining its parts.
- I can apply the spelling change when I add a suffix to a base word.
Standards this unit teaches
- L.4.4.bCommon Core (US)Use affixes and roots as clues to meaning
Use common, grade-appropriate Greek and Latin affixes and roots as clues to the meaning of a word (e.g., telegraph, photograph, autograph).
- RF.4.3.aCommon Core (US)Use morphology to read unfamiliar words
Use combined knowledge of all letter-sound correspondences, syllabication patterns, and morphology (e.g., roots and affixes) to read accurately unfamiliar multisyllabic words in context and out of context.
- L.4.4Common Core (US)Determine the meaning of unknown words
Determine or clarify the meaning of unknown and multiple-meaning words and phrases based on grade 4 reading and content, choosing flexibly from a range of strategies.
- AC9E4LY09Australian Curriculum v9 (ACARA)Phonic and morphemic knowledge to read words
Understand how to use and apply phonological and morphological knowledge to read and write multisyllabic words with more complex letter combinations, including a variety of vowel sounds and known prefixes.
- AC9E4LY10Australian Curriculum v9 (ACARA)Prefixes and suffixes to spell complex words
Understand how to use knowledge of letter patterns, including double letters, spelling generalisations, morphological word families, common prefixes and suffixes and word origins, to spell more complex words.
Prior knowledge
This unit builds on skills students should already have met. Revisit any that are shaky first.
- Context cluesword parts and context are two ways to unlock a hard word, and they work well together
- Antonymsmany opposites are made by adding a prefix, such as happy and unhappy
- Synonymsknowing a base word's meaning helps you judge the new word an affix builds
- Building reading fluencysplitting a long word into known parts makes it quicker to read accurately
Words to teach and display
- Prefix
- a word part added to the front of a base word to change its meaning
- Suffix
- a word part added to the end of a base word to change its meaning or its job
- Base word
- the main word that a prefix or suffix is added to, such as happy in unhappy
- Root
- the core part of a word that carries its main meaning; a base word is a root that can stand alone
- Affix
- the general name for a prefix or a suffix, a part you add to a base word
- Antonym
- a word with the opposite meaning; a prefix like un- or dis- often makes one
Teach it: model, guided practice, independent
The lesson moves from a teacher think-aloud, to building and splitting words together, to using word parts independently. Every example is a real word, so the strategy is practised on words rather than learned as a rule. Say each word aloud, split it into its parts, and show your thinking before asking students to try.
1. Words are built from parts
Open with the big idea: many words are a base word plus an added part. Model splitting a word into its base and its affix, and building one back up, so students see words as made of pieces they can take apart.
Keep the names on the board all unit: base word (the main word), prefix (a part on the front), suffix (a part on the end), and affix (the general name for either).
Model both directions. Build: happy plus the front part un gives unhappy. Split: unlock the long word 'unkindly' by breaking it into un, kind and ly.
Split the word 'unhappy' into its parts and name each one.
- Find the base word you already know: happy.
- Look at what is added to the front: un.
- Name the parts: un is a prefix, happy is the base word.
Answer: Unhappy splits into the prefix un and the base word happy. The prefix on the front changes the meaning to 'not happy'.
- What is a base word?
- Where does a prefix go, and where does a suffix go?
- What is the general name for a prefix or a suffix?
2. Common prefixes
Teach the four most useful prefixes and what each one means. A prefix goes on the front and changes the meaning of the base word. Model adding each to a base word and saying the new meaning.
The four to know: un- means not or the opposite (unlock, unkind), re- means again (redo, rebuild), pre- means before (preview, preheat), and dis- means not or the opposite (disagree, dishonest).
Notice that un- and dis- both make opposites, which is why so many antonyms are built with a prefix. Say the base word, add the prefix, and check the new meaning makes sense.
Add the prefix re- to the base word 'build' and work out the meaning.
- Recall what re- means: again.
- Add it to the base word: re plus build gives rebuild.
- Combine the meanings: again plus build.
Answer: Rebuild means to build again. The prefix re- means again, so it adds that meaning to the base word build.
- What does the prefix un- mean?
- What does re- mean, and what does pre- mean?
- Which two prefixes here often make opposites?
3. Common suffixes
Now teach the suffixes. A suffix goes on the end and changes the meaning or the job of the word. Model adding each to a base word and saying what it does.
The four to know: -ful means full of (hopeful, joyful), -less means without (hopeless, careless), -ly means in that way and often makes an adverb (quickly, slowly), and -ness means the state of being and makes a noun (kindness, sadness).
Point out the neat pair: -ful means full of and -less means without, so hopeful and hopeless are opposites built from the same base word.
Add the suffix -less to the base word 'hope' and work out the meaning.
- Recall what -less means: without.
- Add it to the base word: hope plus less gives hopeless.
- Combine the meanings: without plus hope.
Answer: Hopeless means without hope. The suffix -less means without, so it adds that meaning to the base word hope.
- What does the suffix -ful mean, and what does -less mean?
- What does the suffix -ness do to a word?
- Why are hopeful and hopeless opposites?
4. Use the parts to work out meaning
Bring it together into the reading strategy that matters: unlocking a long, unknown word by combining the meaning of its base with the meaning of its affix. Model breaking a word apart and building the meaning from the pieces.
Give the formula and keep it on the board: base word meaning plus affix meaning equals the word meaning. Split the word first, then add the meanings.
This pairs with context clues. Work out the meaning from the parts, then check it against the sentence to be sure it fits.
Work out what 'preview' means by using its parts.
- Split the word: the prefix pre and the base word view.
- Recall the meanings: pre means before, view means see or look.
- Combine them: before plus see.
Answer: Preview means to see something before, such as watching a short part of a film before it comes out. Pre- means before and view means see, so the parts give the meaning.
- What is the formula for working out a word from its parts?
- What do you do first, split the word or add the meanings?
- How can context clues help you check your answer?
5. Spelling changes when you add a suffix
Finish with the spelling rules. Adding a suffix that starts with a vowel often changes the base word's spelling. Model the three common changes so students spell built words correctly.
The three rules: drop the silent e before a vowel suffix (hope plus ing gives hoping), double the final consonant after a short vowel (run plus ing gives running), and change y to i before most suffixes (happy plus ness gives happiness).
Prefixes are easier: they almost never change the spelling of the base word, so un plus happy is simply unhappy. The tricky changes are mostly on the suffix side.
Add the suffix -ness to the base word 'happy' and spell the new word.
- Look at the base word ending: happy ends in a y.
- Recall the rule: change y to i before the suffix.
- Add the suffix to the changed base: happi plus ness.
Answer: Happy plus -ness gives happiness. The y changes to i before the suffix, so it is spelled happiness, not happyness.
- What happens to a silent e before a suffix that starts with a vowel?
- When do you double the final consonant?
- What change do you make to a base word that ends in y?
Common misconceptions and how to address them
MisconceptionAny group of letters at the start of a word is a prefix.
Why it happens: Students spot 'un' inside uncle or 're' inside red and split words that have no real prefix.
How to address it: Teach the test: take the part off and check a real base word is left. Uncle has no base word 'cle', so un is not a prefix there.
MisconceptionA prefix and a suffix mean the same as the words they sound like.
Why it happens: Students hear 'less' and think of 'less than', or 'ful' and think 'a full cup', rather than the affix meanings.
How to address it: Attach a fixed meaning to each affix: -less means without, -ful means full of. Practise them on base words until the affix meaning is automatic.
MisconceptionYou can add a suffix without ever changing the base word's spelling.
Why it happens: Students add the suffix straight on, writing 'hoping' as 'hopeing' or 'happiness' as 'happyness'.
How to address it: Teach the three changes: drop the e, double the consonant, change y to i. Practise each rule on several words so the change becomes a habit.
MisconceptionWorking out a word from its parts always gives the exact dictionary meaning.
Why it happens: Students trust the parts completely and never check the result against the sentence.
How to address it: Use the parts to get a good estimate, then check it with the context. Combining word parts and context clues is stronger than either alone.
Misconceptionun- and dis- can be swapped because they both mean not.
Why it happens: Both prefixes make opposites, so students write 'unhonest' or 'dishappy'.
How to address it: Show that each base word takes a particular prefix by convention: it is dishonest and unhappy, not the reverse. Build word families and read them aloud so the correct pairing sounds right.
Guided practice (with answers)
1. Split 'disagree' into its parts and name each one. What does it mean?
Answer: Disagree splits into the prefix dis and the base word agree. Dis- means not, so disagree means to not agree.
2. Add the suffix -ful to the base word 'care' and give the meaning.
Answer: Care plus -ful gives careful. The suffix -ful means full of, so careful means full of care, or taking care.
3. Work out what 'preheat' means by using its parts.
Answer: Preheat splits into pre (before) and heat. It means to heat something before, such as heating an oven before you cook.
4. Add the suffix -ing to the base word 'run' and spell it. Which rule did you use?
Answer: Run plus -ing gives running. You double the final consonant after a short vowel, so it is running, not runing.
5. Why is 'un' in the word 'under' not a prefix?
Answer: Take un off and you are left with 'der', which is not a real base word. A prefix must leave a real base word behind, so un in under is not a prefix.
6. What is the formula for working out an unfamiliar word from its parts?
Answer: Base word meaning plus affix meaning equals the word meaning. Split the word first, then add the meanings, and check it against the sentence.
Independent practice worksheets
Set the matching ChalkBee prefix and suffix worksheets for independent work, then have students split longer words into parts and work out their meanings. Ask them to write the base word and the affix separately for each word.
Differentiation
- Work with one affix per lesson, starting with un-, which is the most familiar.
- Give a base word and the affix as physical cards to snap together, so the build is concrete.
- Provide an affix-meaning chart on the desk (un- = not, re- = again, -ful = full of, -less = without).
- Start with words that need no spelling change (unlock, careful) before teaching the three suffix rules.
- Introduce Greek and Latin roots such as tele (far), photo (light) and graph (write), and build words like telegraph and photograph.
- Add a second affix, working out words that have both a prefix and a suffix, such as unkindly or disagreement.
- Sort a word bank into families by base word, showing how one base builds many words.
- Work out a made-up word from real parts, such as 'rebuildable', and explain the meaning from each piece.
Assessment: exit ticket
A three-question exit ticket done on a slip in the last few minutes. It samples splitting a word into parts, working out a meaning from the parts, and applying a suffix spelling rule.
1. Split 'unlock' into its parts and give the meaning.
Answer: Unlock splits into the prefix un and the base word lock. Un- means the opposite, so unlock means to open something that was locked.
2. Work out what 'careless' means by using its parts.
Answer: Careless splits into the base word care and the suffix -less. -less means without, so careless means without care.
3. Add the suffix -ing to the base word 'hope' and spell it. Which rule did you use?
Answer: Hope plus -ing gives hoping. You drop the silent e before a suffix that starts with a vowel, so it is hoping, not hopeing.
Teacher notes and timings
- Rough timing across three lessons: Lesson 1 word parts plus common prefixes (sections 1 and 2), Lesson 2 common suffixes plus using parts to work out meaning (sections 3 and 4), Lesson 3 spelling changes plus the exit ticket (section 5 and assessment).
- Language to keep saying: split it into parts, base word plus affix, then check it. These phrases pre-empt most of the misconceptions.
- This unit teaches the suffix -ness even though the linked worksheets cover -ful, -less and -ly; add your own -ness examples (kindness, sadness, darkness) when you model section 3, since -ness is a high-value noun-making suffix.
- Working out a word from its parts is the sister strategy to context clues, so this unit pairs naturally with the context-clue unit. Teach students to use word parts first and then confirm with the sentence.
- Curriculum note: US Grade 4 sets out affixes and roots for both reading (RF.4.3.a) and meaning (L.4.4.b). In ACARA v9, prefixes and suffixes sit within morphemic knowledge for reading (AC9E4LY09) and for spelling (AC9E4LY10). This unit maps to US Grade 4 and supports the ACARA morphology expectations, which build across the middle and upper primary years.
- Present mode and print both work: use the Print button for a clean teacher copy or a student handout, and project words to split into parts and build together on the screen.