Grade by Grade
B. Foundations of Language · Listening, Speaking and Word Power

Prefixes for Grade 4: inter-, trans-, super-, semi-, multi- and More

B2.1 B2.2About 40 minutes
Learning goals
  • I can read and explain new prefixes: inter-, trans-, super-, semi-, multi-, fore-, de-, anti-, co-, il- and ir-.
  • I can choose between il-, ir-, im- and in- for the meaning not.
  • I can use a prefix and base to figure out a new word in a sentence.
  • I can check that a prefix is a real prefix in that word.

Words to know

prefix
A morpheme added to the front of a base. It changes the meaning.
base
The main meaning part of a word.
international
Between or among nations (countries).
semicircle
Half of a circle.
multicultural
Having many cultures.
irregular
Not regular; not following the usual pattern.

Remember from Grades 2 and 3

You already know many prefixes:

  • un-, dis-, non-, in-, im-: not or the opposite (unkind, dislike, nonstop, incorrect, impossible)
  • re-: again (rebuild) · mis-: wrongly (misread) · pre-: before (preview)
  • over-: too much or above · under-: below or too little · sub-: under · mid-: middle
  • uni-, bi-, tri-: one, two, three

This lesson adds new prefixes you'll meet in Grade 4 books, science and social studies.

Let's start with a road trip

The Trans-Canada Highway goes across Canada. Trans- means across. Now look at these: transport (carry across), transatlantic (across the Atlantic Ocean). Once you know one prefix, you can unlock a whole family of words!

trans-means acrosstransportcarry acrosstransatlanticacross the Atlantic OceanTrans-Canada Highwaygoes across CanadaLearn one prefix, unlock a whole word family.
One prefix, a whole family: trans- means across in every one of these words.
PrefixMeaningExamples
inter-between, amonginternational, interact, intermission
trans-acrosstransport, Trans-Canada, transatlantic
super-above, more than, extrasuperhero, superhuman, superstar
semi-half, partlysemicircle, semifinal, semisweet
multi-manymulticoloured, multicultural, multilingual
fore-before, frontforecast, foresee, forehead
de-remove, undo, downdefrost, decode, de-ice
anti-againstantifreeze, antibacterial
co-together, withcoworker, co-author, cooperate
il-, ir-notillegal, illogical, irregular, irresponsible
New prefixes for Grade 4
semicirclesemi- = halfmulticolouredmulti- = manycoworkersco- = togetherdefrostde- = removefrost removed
Four prefixes you can picture: semi- (half), multi- (many), co- (together) and de- (remove).

Four ways to say not: in-, im-, il-, ir-

They all mean not. The letter after them gives a clue:

  • il- before l: illegal, illogical
  • ir- before r: irregular, irresponsible
  • im- before m, b or p: immature, imbalance, impossible
  • in- before most other letters: incorrect, invisible, incomplete

That's why illegal has two l's: il + legal!

Worked example

Let's use a prefix to find the meaning

Read: The weather forecast says there will be freezing rain tonight.

  1. Find the prefix: fore- means before.
  2. Find the base: cast. Here it means to throw out or send out (like casting a fishing line).
  3. Put it together: a weather forecast sends out information before the weather happens.
  4. Check in the sentence: it tells us about tonight's weather before it comes. Yes!

A forecast is a prediction made before something happens.

Worked example

Let's compare words with the same base

What do national and international mean?

  1. national: nation + al = having to do with one nation (country). Example: Canada's national anthem.
  2. international: inter (between) + nation + al = between or among nations. Example: an international hockey tournament with teams from many countries.

The prefix inter- changes "one country" into "between many countries."

Is it really a prefix?

Cover the letters that look like a prefix. Is the rest a base that fits the meaning?

  • defrost → frost ✅ (remove the frost)
  • desk → sk ❌ (not a prefix)
  • coworker → worker ✅ (someone who works with you)
  • coat → at ❌ (coat doesn't mean together at!)
  • superhero → hero ✅
  • superb → b ❌
Just for fun

What do you call a superhero who is only half finished?

A semi-superhero! (That's two prefixes for the price of one.)

Worked example

Let's read a sentence with several prefixes

Read: At the multicultural festival, the coworkers cooperated to defrost the frozen food.

  1. multicultural: multi (many) + cultural = having many cultures: food, music and traditions from many backgrounds.
  2. coworkers: co (with) + work + er + s = people who work together.
  3. cooperated: co (together) + operate (work) + ed = worked together.
  4. defrost: de (remove) + frost = remove the frost, thaw.
  5. Now read the whole sentence smoothly, chunking each word by its parts.

People who work together helped each other thaw the frozen food at a festival with many cultures.

Hands-on activity

Prefix hunt around the house

You need: paper, a pencil and 15 minutes.

  1. Hunt for prefix words on things at home: cereal boxes, cleaning-product labels (look only; don't open them), medicine boxes (look only), game boxes, the TV guide, books and magazines. Examples you might find: antibacterial, multigrain, preheat, reusable, international, superstore, defrost (on a microwave!).
  2. Write each word you find. Underline the prefix and box the base.
  3. Next to each word, write the meaning by adding the parts.
  4. Find at least 8 words. Which prefix did you find most often?

Safety: look at labels only. A grown-up should handle cleaning products and medicines.

Your turn

1

What does semi- mean? Read semicircle.

2

Read transport. What does it mean?

3

Add a prefix meaning not to legal.

4

What does multilingual mean?

5

Read: We will defrost the turkey for Thanksgiving. What does defrost mean?

6

What does interact mean?

7

Is co- a prefix in coat? How do you know?

More practice: warm-up

1

What does inter- mean?

2

What does multi- mean?

3

What does anti- mean?

4

Find the prefix in forehead.

5

What does irregular mean?

More practice: on your own

1

Which prefix means not for each word: ___responsible, ___logical, ___complete, ___patient?

2

Explain the difference between a final and a semifinal.

3

Read: The antibacterial soap helps stop germs. Use the prefix to explain the word.

4

What does a coworker do? Write the word sum.

5

Use superhuman in a sentence that shows its meaning.

Challenge

1

Read interprovincial. Use the parts to explain it, and give an example.

2

Sort these words by whether they have a real prefix: defrost, desk, cooperate, coach, transport, trance.

3

Invent a sentence that uses three prefixes from this lesson correctly. Then explain each one.

Check your understanding

Quiz

1.

What does trans- mean?

2.

Which word means between nations?

3.

Which is spelled correctly?

4.

What is a semicircle?

5.

In which word is de- a real prefix?

6.

What does multicoloured mean?

7.

What does a weather forecast do?

For parents and teachers

Big idea: Grade 4 B2.1 and B2.2 ask students to use morphemes, including prefixes, to read words and to analyze and understand new words in context. Knowing about 20 common prefixes unlocks a huge number of words in science, social studies and math.

How to help at home:

  • Notice prefixes in everyday words: defrost on the microwave, multigrain bread, an international flight.
  • Play "prefix ping-pong": you say a prefix, your child says a word that uses it and its meaning.

Common difficulties:

  • Fake prefixes (desk, coat, uncle). Teach the cover-and-check test.
  • Mixing up il-, ir-, im-, in-. Point to the first letter of the base.
  • semi- vs. multi- vs. super-. Make a quick chart with a drawing for each.

Safety: In the prefix hunt, labels on cleaning products and medicines are for looking only; a grown-up handles them.