Grade by Grade
B. Foundations of Language · Foundations of Language: Listening, Speaking, Words, Fluency and Conventions

Reading and Spelling Complex Words by Their Parts: Word Sums, Bases and Chameleon Prefixes

B2.1 B2.2About 65 minutes
Learning goals
  • I can break a complex word into its morphemes (prefixes, bases and suffixes) to read it accurately.
  • I can write word sums to show how a word is built.
  • I can explain double letters in words like accommodate, misspell and irregular using prefixes.
  • I can use morphemes to spell commonly misspelled high school words correctly and automatically.

Words to know

morpheme
The smallest part of a word that has meaning: a prefix, a base or a suffix.
base
The morpheme that carries a word's core meaning. A free base can stand alone (count); a bound base cannot (struct in construct).
word sum
A way of showing how a word is built: mis + spell + ing → misspelling.
assimilated (chameleon) prefix
A prefix whose last letter changes to match the first letter of the base, as in- becomes ir- in irregular.
automaticity
Being able to read or spell something quickly and accurately without having to stop and think.
syllable
A unit of sound with one vowel sound: in·ter·pret has three. Syllables and morphemes don't always line up.

Remember from earlier grades

You've been writing word sums since Grade 3, met chameleon prefixes (com-, con-, col-, cor-, ad-) in Grade 5 and Grade 6, and in Grade 8 you saw how suffixes can shift a word's sound, stress and spelling while the family keeps its meaning. In Grade 9 you'll meet longer words than ever: in textbooks, novels and tests. This lesson brings those skills together so you can read long words accurately and spell the words that trip up even adults.

Let's start with a challenge

Read this word aloud: uncharacteristically.

Twenty letters is a lot to sound out letter by letter. But if you spot the parts, it's easy: un + character + istic + al + ly. You already know every part. Readers who do this quickly and automatically read complex words with accuracy and automaticity, which leaves their brain free to think about meaning.

uncharacteristically = un + character + istic + al + lyunprefixnotcharacterbasequalitiesisticsuffixtypical ofalsuffixrelating tolysuffixin a wayMeaning: in a way that is not typical of someone’s usual qualities.Read it part by part: un · char · ac · ter · is · ti · cal · ly
A 20-letter word is just five familiar morphemes. Find the parts, read each one, then blend. Notice that the syllables (bottom line) don't match the morphemes exactly, and that's fine.

Peel and rebuild: a strategy for long words

  1. Peel off prefixes from the front: un-, mis-, re-, inter-, dis-, in- and their chameleon forms.
  2. Peel off suffixes from the end, one layer at a time: -ly, -al, -ic, -ness, -tion, -able, -ity.
  3. Find the base that's left. Is it a word you know (character, count, interpret) or a bound base you've studied (struct, port, cess, mod)?
  4. Read each part, then blend them into one word, checking the stress sounds natural.
  5. Check the meaning: build it from the parts and test it in the sentence.

Example: misinterpretation → mis + interpret + ation → "the act of interpreting wrongly."

Chameleon prefixes explain double letters

Many "spelling demons" have double letters near the start. They aren't random. They happen when a prefix's last letter changes to match the base (the prefix is assimilated). This makes the word easier to say: inregular is awkward, irregular is smooth.

  • in- (meaning not) becomes im- before b, m, p, il- before l, and ir- before r: immature, illegal, irregular, irresponsible.
  • ad- (meaning to, toward) becomes ac-, af-, al-, ap-, as-, at-: accommodate, affect, allocate, approve, assist, attract.
  • sub- becomes suc-, suf-, sup-: success, suffix, support.
  • com-/con- becomes col-, cor-: collect, correct.
  • ob- becomes oc-: occur.

And sometimes a double letter happens simply because one part ends with the letter the next part starts with: mis + spell = misspell, un + necessary = unnecessary, dis + satisfied = dissatisfied.

in- (not) changes to…ad- (to, toward) changes to…in-im- before b, m, pimmatureil- before lillegalir- before rirregularad-ac-accommodateaf-affectal-allocateap-approveas-assistat-attractThe last letter of the prefix copies the first letter of the base. That is why these words have double letters.
Two chameleon prefixes. When you know the prefix and the base, you know the double letter is coming.
Spelling demonWord sumWhy it's spelled that way
accommodateac (ad) + com + mod + atead- becomes ac- before c (two c's); com + mod gives two m's
recommendre + com + mendone c (only re- comes first); com + mend gives two m's
necessaryne + cess + aryone c, two s's: the base is cess, as in process
occurrenceoc (ob) + cur + r + enceob- becomes oc- (two c's); the r doubles because CUR is stressed
misspellmis + spelltwo s's because mis ends in s and spell starts with s
definitelyde + fin + ite + ly-ite, not -ate: think of finite (fin = end)
separatese + par + atepar as in prepare: there's a rat in sep-a-rate
successsuc (sub) + cesssub- becomes suc-, so c doubles; cess as in process
Commonly misspelled words explained by their morphemes. Once you see the parts, the spelling makes sense.
Worked example

Let's read and spell a complex word

Read and spell irreplaceable, and explain its meaning.

  1. Peel the prefixes: ir- (the chameleon form of in-, meaning not, before r) and re- (again).
  2. Peel the suffix: -able (can be).
  3. Find the base: place.
  4. Word sum: ir (in) + re + place + able → irreplaceable. The double r comes from ir + re. The e in place stays because -able follows a soft c (you'll study this in the next lesson).
  5. Read: ir · re · place · a · ble. Meaning: not able to be replaced.

Irreplaceable = ir (in, "not") + re + place + able: "cannot be replaced." Two r's from the chameleon prefix; e kept after the soft c.

Spell by meaning, not just by sound

When you aren't sure of a spelling, ask: what are the parts? The sound of necessary doesn't tell you how many c's or s's it has, but the morphemes do (ne + cess + ary). Meaning-based spelling works on the words that sound-based spelling gets wrong.

Hands-on activity

Spelling demon detective

You need: paper, a pen, and one of your textbooks or a novel.

  1. Find 8 words of at least four syllables in the book.
  2. For each, write a word sum showing prefixes, base and suffixes.
  3. Circle any double letters and explain them: chameleon prefix? Two parts meeting? Doubling before a suffix?
  4. Choose the 3 hardest words. Cover them, have a family member say them, and spell them from your word sums.
  5. Make a "demon list" on a sticky note with the word sum for any word you misspelled, and keep it in your binder.
Just for fun

The word misspell has a sense of humour: if you write it with one s, you have misspelled misspell. Remember mis + spell: each part brings its own s.

Your turn

1

Write a word sum for unpredictability.

2

Explain the double l in illegal.

3

Explain the double m in recommend.

4

Read and give the meaning of disproportionately.

5

Which is spelled correctly: neccessary, necessary or necesary? Explain with the word sum.

6

Explain the double c in accommodate.

7

Write the word sum for misinterpreted and read it in parts.

More practice: warm-up

1

What are the three kinds of morphemes?

2

What does the prefix in- mean in incomplete?

3

Before which letters does in- become im-?

4

Write the word sum for unnecessary.

5

Is struct a free base or a bound base?

More practice: on your own

1

Explain why irresponsible has two r's but unresponsive has one.

2

Write word sums for affect and effect. What do they share?

3

A classmate spells occurence. Use morphemes and stress to explain the correct spelling.

4

Read and define counterproductive using its parts.

5

Explain how knowing the base fin (end) helps you spell definitely and infinite.

Challenge

1

Write the word sum for indistinguishable and explain how you'd read it fluently.

2

Find the chameleon prefix in each word and name the original form: suppress, collaborate, attract, occasion.

3

A friend says, "English spelling is completely random." Use three examples from this lesson to argue that it often isn't.

Check your understanding

Quiz

1.

Which word sum is correct for misspelling?

2.

Why does irregular have two r's?

3.

Which word contains an assimilated (chameleon) form of ad-?

4.

Necessary is spelled with:

5.

In uncharacteristically, the base is:

6.

What does automaticity in reading mean?

For parents and teachers

Big idea: Expectation B2.1 asks students to use consolidated knowledge of morphemes (bases, prefixes and suffixes) to read and spell complex words with accuracy and automaticity.

How to help at home: When your teen misspells a long word, don't just correct it. Ask, "What are the parts?" and write the word sum together. Keep a short "demon list" on the fridge.

Common difficulties:

  • Sounding out letter by letter instead of spotting parts.
  • Missing double letters from chameleon prefixes (acommodate, ilegal).
  • Adding letters that aren't there (neccessary). The word sum shows exactly how many letters each part has.
  • Mixing up syllables and morphemes. They don't always line up, and that's normal.