B. Foundations of Language · Listening, Speaking and Word PowerPrefixes for Grade 5: Number, Measurement, Position and Chameleon Prefixes
B2.1 B2.2 A3.1About 45 minutes
Learning goals- I can read and explain number prefixes such as mono-, quad-, pent-, hex-, oct-, dec-, cent-, kilo-, milli- and poly-.
- I can use number prefixes to understand math and measurement words.
- I can read and explain the prefixes post-, circum-, extra-, counter- and en-/em-.
- I can recognize a chameleon prefix, like con- changing to com-, col- or cor-.
- I can use a prefix and the context to figure out a new word.
Words to know
prefix
A morpheme added before a base that changes its meaning.
polygon
A closed flat shape with straight sides. poly (many) + gon (angle).
metric prefix
A prefix in a metric unit that tells its size, like kilo- in kilometre.
chameleon prefix
A prefix that changes its last letter to match the start of the base, like con- becoming com- in compare.
circumference
The distance around a circle. circum (around) + fer (carry) + ence.
Remember from Grades 2 to 4
In Grades 2 and 3 you learned un-, re-, dis-, pre-, mis-, sub- and the number prefixes uni- (one), bi- (two) and tri- (three). In Grade 4 you added inter-, trans-, super-, semi-, multi-, fore-, de-, anti-, co- and the not prefixes il- and ir- (alongside in- and im-). In Grade 5 you'll learn more number prefixes (very useful in math and science), some new position prefixes, and chameleon prefixes that change their spelling.
Let's start with a puzzle
What do an octopus, an octagon (like a stop sign) and the month of October have in common?
They all start with oct-, which means eight. An octopus has eight arms, and an octagon has eight sides. October was the eighth month in the old Roman calendar (it's now the tenth, because two months were added later). One small prefix, three words!
Number prefixes
| Prefix | Means | Examples |
|---|
| mono- | one | monorail, monologue (one person speaking) |
| uni-, bi-, tri- (review) | one, two, three | unicycle, bicycle, triangle |
| quad-, quadr- | four | quadrilateral (four sides), quadruple |
| pent-, penta- | five | pentagon |
| hex-, hexa- | six | hexagon |
| oct-, octo- | eight | octagon, octopus |
| dec-, deca- | ten | decade (ten years), decagon |
| cent- | hundred | century (100 years), centipede, cent (1/100 of a dollar) |
| poly- | many | polygon, polyhedron |
| multi- (review) | many | multicultural |
Metric prefixes: Canada measures with them!
Canada uses the metric system, and its units are built with prefixes on a base like metre or gram:
| Prefix | Means | Example | How big |
|---|
| kilo- | one thousand | kilometre (km), kilogram (kg) | 1 km = 1000 m |
| centi- | one hundredth | centimetre (cm) | 100 cm = 1 m |
| milli- | one thousandth | millimetre (mm), millilitre (mL) | 1000 mm = 1 m |
Position and other prefixes
| Prefix | Means | Examples |
|---|
| post- | after | postpone (put off until after), postwar, P.S. (postscript: written after) |
| circum- | around | circumference, circumnavigate (sail around) |
| extra- | beyond, outside | extraordinary, extracurricular, extraterrestrial |
| counter- | against, opposite | counterclockwise, counteract |
| en-, em- | put into, cause to be | endanger, enlarge, encircle, empower |
Chameleon prefixes
A chameleon changes colour to match where it is. Some prefixes change their last letter to match the base, because it's easier to say. You saw this in Grade 4: in- becomes im- (impossible), il- (illegal) or ir- (irregular).
The prefix con- (with, together) does the same:
- con- → conduct, connect, construct
- com- (before b, m, p) → combine, commit, compare
- col- (before l) → collect, collaborate
- cor- (before r) → correspond, correlate
When you see com-, col- or cor- at the start of a long word, think together or with: collaborate = labour together.
Just for funIf a bicycle has two wheels and a tricycle has three, an octocycle would have eight. Good luck parking it at school!
Worked exampleLet's figure out a math word
Read: A square, a rectangle and a rhombus are all quadrilaterals.
- Prefix: quadr- means four.
- Base: later means side (like lateral, bilateral).
- Suffix: -al means having to do with; -s means more than one.
- Word sum: quadr + i + later + al + s → quadrilaterals (the i is a connecting letter).
- Meaning: shapes that have four sides.
- Check with context: squares, rectangles and rhombuses all have four sides. It fits!
quadrilateral = a shape with four sides.
Worked exampleLet's use a prefix and context together
Read: The hockey game was postponed because of the ice storm. It will be played next Saturday instead.
- Prefix: post- means after.
- Base: pone means put (as in component, opponent).
- Meaning from parts: put after: moved to a later time.
- Context check: "It will be played next Saturday instead" shows the game moved to a later date.
postponed = moved to a later time.
Check that it's really a prefix
Not every oct or post is a prefix. A post in a fence and poster aren't after words. Ask: Does the meaning of the prefix fit the whole word?
Hands-on activityPrefix scavenger hunt around the house
You need: paper, a pencil, a ruler or measuring tape, and food packages from the cupboard.
- Look at food labels and the ruler. Find and write words or symbols with kilo-, centi- or milli- (for example kg, g, mL, cm, mm). Write what each prefix means.
- Look around the house and outside for shapes: a stop sign (octagon), a tile, a nut or a honeycomb cereal piece (hexagon). Name each shape with its prefix.
- Find a clock and move your finger clockwise, then counterclockwise.
- Write five words with prefixes from this lesson and draw a quick picture clue for each.
Safety: if you look outside for a stop sign, stay on the sidewalk with a grown-up.
What to look for: correct prefix meanings (kilo = thousand, milli = thousandth) and shapes named by the number of sides.
Your turn
1What does poly- mean? Name a word that uses it.
many. Example: polygon (a shape with many angles and sides).
2How many sides does a hexagon have?
3How many years are in a decade? In a century?
A decade = 10 years. A century = 100 years.
4What does kilo- mean in kilometre? How many metres is that?
one thousand. 1 kilometre = 1000 metres.
5Read: Astronauts have circumnavigated Earth thousands of times. What does it mean?
circum- (around) + navigate (steer, travel): travelled all the way around.
6What does extracurricular mean? (Hint: the curriculum is what you learn in class.)
Outside or beyond regular class learning, like after-school clubs and sports teams.
7Which prefix fits? The volunteers want to ______power young people to help their community. (en / em)
empower, because the base starts with p.
More practice: warm-up
3How many sides does a pentagon have?
4Which is longer: a millimetre or a centimetre?
A centimetre (10 mm = 1 cm).
5What does counter- mean in counterclockwise?
opposite (against): the opposite direction to the way clock hands turn.
More practice: on your own
1Explain why cent means one hundred in century but centi means one hundredth in centimetre.
Century is 100 years (one hundred). A centimetre is one of the 100 equal parts of a metre, so it's one hundredth of a metre. Both are about the number 100.
2Read collaborate. What is the chameleon prefix, and what does the word mean?
col- (a form of con-, together) + labor (work) + ate: to work together.
3A monorail and a monologue: what do they have in common?
Both use mono- (one): a monorail runs on one rail, and a monologue is one person speaking.
4Read: The flooding endangered homes near the river. Explain with the prefix.
en- (put into, cause to be) + danger + ed: put the homes in danger.
5A polygon has 10 sides. What is its name? Explain.
A decagon: dec- means ten, -gon means angle (and a polygon has the same number of angles as sides).
Challenge
1A math word is polyhedron (hedron = face or side). What is it? Give an example from your home.
A 3-D shape with many flat faces. Examples: a cereal box (rectangular prism), a die (cube), a tissue box. A ball is not one, because it has no flat faces.
2Explain why we write compare but conduct. Use the idea of chameleon prefixes.
Both use the prefix con- (with, together). Before p, con- changes to com- because com-p is easier to say than con-p. Before d, it stays con-.
3A kilogram of apples weighs the same as how many grams? A road sign says 3 km to the next town. How many metres? Explain using the prefix.
Kilo- means one thousand, so 1 kilogram = 1000 grams and 3 km = 3 × 1000 = 3000 metres.
Quiz
2. What does circumference measure?
3. How many millimetres are in one metre?
5. Which word has a chameleon form of con-?
7. Which prefix means beyond or outside?
Big idea (B2.1, B2.2): Grade 5 students use morphology to read and understand complex words, including vocabulary from other subjects. Number and metric prefixes link directly to Grade 5 math (polygons, metric measurement), connecting to A3.1 (language in other subjects).
How to help at home:
- Read food labels together: kg, g, mL, L. Ask what kilo- and milli- mean.
- Name shapes you see on walks: stop signs (octagons), honeycomb patterns (hexagons).
- When you see com-, col- or cor-, ask "Does together or with fit?"
Common difficulties:
- Mixing up centi- and cent- (hundredth vs hundred). Use money: 1 cent is one hundredth of a dollar, and there are 100 cents in a dollar.
- Calling every word that starts with these letters a prefix (post office, decent). Check that the meaning fits.
- Forgetting that em- comes before b, m, p. Say enpower and empower aloud: which is easier?