B. Foundations of Language · Spelling, Grammar and Punctuation

Science Plurals and Canadian Spelling

B2.1 D2.6About 45 minutes

Learning goals

I can spell plurals of words ending in o, like potatoes and pianos.
I can spell science plurals that come from Latin and Greek, like fungi and larvae.
I can use Canadian spellings like colour, centre, travelled and practise.
I can explain how suffixes change Canadian words, like humour → humorous.

Words to know

plural
A word that names more than one: cats, potatoes, fungi.

inflectional suffix
A suffix that changes a word's number or tense but not its basic meaning, like -s, -es, -ed, -ing.

Canadian spelling
The spellings used in Canada. They mix British spellings (colour, centre) and American ones (organize, tire).

noun
A word that names a person, place, thing or idea.

verb
A word that shows an action or a state of being.

Remember from Grade 3

In Grade 3 you learned the main plural patterns: add -s (cats), add -es after s, x, z, ch, sh (boxes, lunches), change y to i and add -es after a consonant (cities), change f or fe to v and add -es (leaves, knives), and learn the irregular ones (children, mice, geese).

In Grade 5 you'll learn three new spelling skills: plurals of words ending in o, science plurals from Latin and Greek, and Canadian spelling.

Words ending in o

Vowel + o: just add -s: radio → radios, video → videos, kangaroo → kangaroos, studio → studios.
Consonant + o: some add -es. Learn these common ones: potato → potatoes, tomato → tomatoes, hero → heroes, echo → echoes, volcano → volcanoes, mosquito → mosquitoes.
Short forms and music words usually just add -s: photo → photos (from photograph), piano → pianos, solo → solos, auto → autos.

Some o words can be spelled both ways (volcanoes or volcanos). When you're not sure, a dictionary shows the plural right after the word.

Three groups of o words. Most just add -s; a few everyday consonant + o words add -es, and those are worth memorizing.

A memory sentence

My heroes eat potatoes and tomatoes. These three everyday words all add -es. The words photos and pianos don't.

Science plurals from Latin and Greek

Some science words kept the plural endings from Latin and Greek. You'll see them in science books and on museum signs.

One	More than one	Pattern
fungus	fungi	-us → -i
cactus	cacti (or cactuses)	-us → -i
larva	larvae	-a → -ae
antenna (on an insect)	antennae	-a → -ae
crisis	crises	-is → -es
phenomenon	phenomena	-on → -a

Science plurals

Worked example

Let's use a science plural

Complete the sentence: We found many ______ (fungus) growing on the old log after the rain.

fungus ends in -us. It's a Latin science word.
Latin -us words often change to -i in the plural.
fungus → fungi.

We found many fungi growing on the old log after the rain.

Canadian spelling

Canada's spelling is a mix. We share some spellings with Britain and some with the United States. Here are the Canadian patterns:

-our: colour, neighbour, favourite, honour, behaviour, flavour
-re: centre, theatre, metre, litre, fibre
Doubled l before a suffix: travel → travelled, travelling, traveller; cancel → cancelled; label → labelled; model → modelling
Noun with c, verb with s: practice (noun) / practise (verb); licence (noun) / license (verb). (advice/advise work the same way everywhere.)
Like Americans, Canadian dictionaries usually use -ize: organize, realize, recognize. And we write tire (on a car) and program.
cheque (to pay with) and grey.

Canadian spelling borrows from both British and American spelling. Using -our, -re and doubled l, plus -ize, is what makes it Canadian.

Noun (a thing)	Verb (an action)
Hockey practice* starts at 6.*	I practise* my slap shot every day.*
Dad renewed his driver's licence.	The city will license* the new food truck.*
Thanks for the advice.	I advise* you to wear a helmet.*

c for the noun, s for the verb

A trick for practice and practise

Ice is a noun, and practice, licence, advice use the c like ice when they are nouns. When it's something you do, switch to s.

Worked example

Let's check Canadian spelling in a sentence

Edit for Canadian spelling: My favorite thing about our neighborhood is the community center, where I practice piano.

favorite → favourite (-our).
neighborhood → neighbourhood (-our).
center → centre (-re).
practice is used as a verb here (something I do), so → practise.

My favourite thing about our neighbourhood is the community centre, where I practise piano.

Just for fun

One goose, two geese. One tooth, two teeth. So why isn't it one moose, two meese?

Nope: it's one moose, two moose. English just likes to keep you guessing!

A sneaky suffix change

When you add -ous or -ary to an -our word, the u drops out: humour → humorous, vigour → vigorous, honour → honorary. But with most other suffixes it stays: colourful, honourable, favourite.

Hands-on activity

Canadian spelling hunt

You need: paper, a pencil, and some Canadian print: a cereal box, a flyer, a newspaper, a local library website, or a product label.

Make four columns: -our, -re, doubled l, science and o plurals.
Hunt for words in each column. Write them down.
Look at a product made for both Canada and the U.S. Do you see colour on one side and color somewhere else? Many Canadian packages are printed in English and French, so look carefully!
Ask a grown-up to read three practice/practise or licence/license sentences aloud. You hold up a card that says C (noun) or S (verb).

Your turn

Write the plural: potato.

Write the plural: radio.

Write the plural: larva.

Write the Canadian spelling: color.

Write the Canadian spelling: theater.

Add -ed to travel (Canadian spelling).

Choose: Soccer (practice / practise) is on Tuesday.

More practice: warm-up

Write the plural: piano.

Write the plural: hero.

Write the plural: fungus.

Write the Canadian spelling: neighbor.

Write the Canadian spelling: liter.

More practice: on your own

Choose: I need to (practice / practise) my lines for the play. Explain.

Edit for Canadian spelling: The trip was cancelled because of the snow storm at the theater.

Write the plural of volcano and video. Explain the difference.

A moth has two feelers called antennae. What's the singular?

Choose: My doctor gave me good (advice / advise). Explain.

Challenge

Explain why humorous has no u after the o, but colourful does.

Fix all the spelling errors (Canadian spelling): Our class labeled the cactuses and funguses in the science center, then the travelers visited the theater.

Write two sentences: one with licence and one with license. Explain your choices.

Check your understanding

Quiz

Which plural is spelled correctly?

What is the plural of fungus in science?

Which is the Canadian spelling?

Which sentence is correct in Canadian spelling?

Which is the Canadian spelling?

What is humour + -ous?

For parents and teachers

Big idea (B2.1, D2.6): Grade 5 students use knowledge of morphemes, including inflectional suffixes like plural -s/-es, to spell accurately, and they edit for spelling. Canadian spelling is a real feature of the texts children read here: colour, centre, travelled, practise. Science plurals (fungi, larvae) appear in Grade 5 science.

How to help at home:

Point out Canadian spellings on signs, menus and packaging.
Check that your devices are set to English (Canada) so spell-checkers support these spellings.
For practice/practise, ask: "Is it a thing or an action?"

Common difficulties:

Adding -es to every o word (pianoes, photoes). Learn the short list that takes -es; most others take -s.
Mixing American and Canadian forms in one piece. Pick Canadian and stay consistent.
practice/practise. Even adults mix these up; the noun/verb test is the key.
Some words have two accepted spellings (cacti/cactuses, volcanoes/volcanos). Either is fine if it's in a Canadian dictionary.