B. Foundations of Language · Spelling, Grammar and PunctuationTricky Endings: -cial or -tial? -cious or -tious? -ary, -ery or -ory?
B2.1About 45 minutes
Learning goals- I can choose -cial or -tial by looking at a related word.
- I can choose -cious or -tious by looking at a related word.
- I can use clues to choose -ary, -ery or -ory.
- I can spot the exceptions and check a dictionary when no clue works.
Words to know
suffix
A morpheme added to the end of a base to change its meaning or its job.
related word
A word in the same family, which often shows how to spell the ending.
exception
A word that doesn't follow the usual pattern.
Remember from Grades 4 and 5
You learned to choose -tion or -sion (Grade 4), and -able/-ible, -ant/-ent and -ance/-ence (Grade 5) by looking at the base or a related word. Now let's use the same detective work on three more pairs of endings that sound alike.
-cial or -tial? (both say /shul/)
Look at a related word:
- If it ends in t, use -tial: part → partial, president → presidential, torrent → torrential.
- If it ends in -ence, use -tial: essence → essential, confidence → confidential, influence → influential.
- If it ends in another -ce (like -ace, -ice, -ince, -erce), use -cial: face → facial, office → official, finance → financial, province → provincial, commerce → commercial.
Exceptions: space → spatial and substance → substantial. If there's no related word, check a dictionary: special, social and crucial use -cial, but initial uses -tial.
-cious or -tious? (both say /shus/)
The same trick works:
- Related word ends in -ce or -cion → -cious: space → spacious, grace → gracious, malice → malicious, suspicion → suspicious.
- Related word ends in -tion → -tious: caution → cautious, ambition → ambitious, nutrition → nutritious, infection → infectious.
No related word? delicious and precious use -cious.
Notice: space gives spacious (with c) but spatial (with t). Even the patterns have surprises!
| Ending | Clue (usually) | Examples |
|---|
| -ery | Added to a whole word you can hear | bakery, bravery, scenery, machinery, greenery |
| -ory | A related word ends in -or | director → directory, inventor → inventory, predator → predatory, sensor → sensory |
| -ary | A very common ending; try it when no other clue fits | library, temporary, necessary, vocabulary, January, February |
Worked exampleLet's choose -cial or -tial
Spell the word that means about a province: provin___.
- Think of the related word: province.
- It ends in -ce, but not -ence. (It's -ince.)
- Words related to -ce (not -ence) usually use -cial.
- Check by saying it: pro-VIN-shul. Province → provincial.
provincial, as in a provincial park.
Worked exampleLet's choose -ary, -ery or -ory
A store counts everything on its shelves. Spell the word for that list: invent___.
- Is there a related word ending in -or? Yes: inventor.
- The clue says a related -or word points to -ory.
- Say it: IN-ven-tor-ee. It matches: inventory.
inventory (think inventor). For words with no clear clue, like migratory (birds that fly south in fall), check a dictionary.
Clues, not laws
These are clues, not laws. Use them to make your best spelling choice, then check in a dictionary or with a spell-checker for words you're unsure of. Good spellers check!
Just for funRiddle: What is delicious, nutritious and a little bit suspicious?
The last cookie in the jar when nobody remembers leaving it there!
Hands-on activityEnding sort with flyer and cereal-box words
You need: paper, a pencil, and a flyer, a newspaper, food packaging or a book.
- Make five columns: -cial, -tial, -cious, -tious and -ary/-ery/-ory.
- Hunt for words with these endings. Food packaging is great for nutritious, delicious and artificial. Flyers may have special, official and bakery.
- Write each word in its column. Beside it, write a related word if you can find one (nutrition → nutritious).
- Circle any exceptions you find.
- Make up a silly sentence using four of your words, like The ambitious chef made a delicious, nutritious, spacious cake.
Your turn
1Choose -cial or -tial: offi___. Explain.
official. The related word office ends in -ce.
2Choose -cial or -tial: par___. Explain.
partial. The related word part ends in t.
3Choose -cial or -tial: confiden___. Explain.
confidential. The related word confidence ends in -ence.
4Choose -cious or -tious: cau___. Explain.
cautious. The related word caution ends in -tion.
5Choose -cious or -tious: gra___. Explain.
gracious. The related word grace ends in -ce.
6Choose -ary, -ery or -ory: brav___.
bravery: brave is a whole word.
7Choose -ary, -ery or -ory: direct___ (a list of names and addresses).
directory: the related word director ends in -or.
More practice: warm-up
1Spell: fa___ (about the face).
2Spell: nutri___ (full of nutrition).
3Spell: bak___ (a place where bread is baked).
5Spell: spa___ (having lots of space).
More practice: on your own
1Spell the adjective for finance, and explain.
financial. finance ends in -ce (not -ence), so use -cial.
2Spell the adjective for influence, and explain.
influential. influence ends in -ence, so use -tial.
3Spell the adjective for suspicion, and explain.
suspicious. suspicion ends in -cion, so use -cious.
4Spell the noun that means a list of everything a store has (related to inventor).
inventory. The related word ends in -or, so -ory.
5Spell: the mach___ in the factory (many machines). Explain.
machinery. machine is a whole word, so -ery (drop the e: machin + ery).
Challenge
1space gives two adjectives: spa___ (having lots of room) and spa___ (about space and position, as in spatial sense in math). Spell both and explain why this is tricky.
spacious (with c, following the -ce → -cious clue) and spatial (with t, an exception to the -ce → -cial clue). It's tricky because the same base uses both c and t. When a word breaks the pattern, memorize it or check a dictionary.
2Find and fix the three spelling mistakes: The ambicious team ate a nutricious lunch in the provintial park.
ambitious (ambition ends in -tion), nutritious (nutrition ends in -tion), provincial (province ends in -ce).
3Explain why sensory uses -ory but bravery uses -ery.
sensory has a related word ending in -or (sensor), which points to -ory. bravery is the whole word brave plus -ery (drop the e).
Quiz
1. Which spelling is correct?
2. Which spelling is correct?
3. Which spelling is correct?
4. Which ending fits scen___ (the view of a landscape)?
5. Which word is an exception to the -ce → -cial clue?
6. Which ending fits predat___ (an animal that hunts others)?
Big idea (B2.1): Grade 6 students spell complex words by using what they know about morphemes. Endings that sound the same (/shul/, /shus/, /er-ee/) are easier when students look for a related word.
How to help at home:
- Food labels are full of these words (nutritious, delicious, artificial, official). Read them together.
- When your child misspells an ending, ask: "Is there a related word that shows the spelling?"
- Treat the patterns as clues. Praise your child for checking a dictionary.
Common difficulties:
- Writing -shus or -shul as it sounds. Remind them in these endings the sounds are almost always spelled with c or t (a few rare words, like controversial and anxious, use other letters).
- Exceptions like spatial and substantial. Keep a short "rule breakers" list.
- -ary/-ery/-ory. This is genuinely tricky, even for adults. The clues help most of the time; the dictionary helps the rest.