B. Number · Number Sense: Numbers to 50 and Fractions

Reading, Writing and Showing Numbers to 50

B1.1About 30 minutes

Learning goals

I can read numbers up to 50.
I can write numbers up to 50 with digits and with words.
I can show a number in different ways.
I can tell how numbers are used in everyday life.

Words to know

digit
One of the ten symbols we use to write numbers: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.

number word
A number written with letters, like twelve or thirty-four.

represent
To show a number in a way that makes sense, like with a drawing, ten frames or blocks.

tally mark
A line drawn to count something. Every fifth tally crosses the other four.

Numbers are everywhere!

Look around your home. Can you find any numbers? You might see numbers on a clock, a calendar, a phone, a cereal box or the front door of your house.

Today you will learn to read and write numbers up to 50, and to show them in lots of different ways.

Writing numbers with digits

We use only ten digits to write every number: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.

Numbers up to 9 use one digit. Numbers from 10 to 50 use two digits.

In a two-digit number, the order of the digits matters a lot! 13 and 31 use the same digits, but they are very different numbers. 13 is a little more than ten. 31 is more than thirty!

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13 is 1 ten and 3 more.

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31 is 3 tens and 1 more. That's much bigger than 13!

Reading and writing number words

Here are the number words from 1 to 20. Some of them are tricky. Eleven and twelve don't sound like "one-teen" or "two-teen". The numbers 13 to 19 end in -teen, which means "and ten".

Number	Word	Number	Word
1	one	11	eleven
2	two	12	twelve
3	three	13	thirteen
4	four	14	fourteen
5	five	15	fifteen
6	six	16	sixteen
7	seven	17	seventeen
8	eight	18	eighteen
9	nine	19	nineteen
10	ten	20	twenty

Number words from 1 to 20.

After 20, the number words follow a pattern. First say the tens word, then the ones word, with a little line (a hyphen) between them.

Tens	Tens word	Example
20	twenty	24 = twenty-four
30	thirty	37 = thirty-seven
40	forty	41 = forty-one
50	fifty	50 = fifty

The tens words. Notice that forty has no u in it!

Worked example

Reading a number word

Write thirty-six using digits.

Look at the first part: thirty. That means 3 tens, so the first digit is 3.
Look at the second part: six. That means 6 ones, so the second digit is 6.
Put them together: 3 then 6.

thirty-six = 36

Worked example

Writing a number word

Write 27 in words.

The first digit is 2. It tells us there are 2 tens. 2 tens is twenty.
The second digit is 7. That is seven.
Put the words together with a hyphen.

27 = twenty-seven

Watch out!

Write the number the way you say it: "twenty-seven" is 2 tens and 7, so write 27, not 207. A number up to 50 never has more than two digits!

Showing a number in many ways

A number can be shown in lots of ways. They all mean the same amount. Let's look at 18.

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Ten frames: one full ten frame and 8 more makes 18.

⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐

Objects: a row of 10 stars and a row of 8 stars. 10 and 8 is 18.

On a number line, 18 is two spaces before 20.

Tally marks: three bundles of 5 and 3 more. Count by 5s, then 1s: 5, 10, 15, 16, 17, 18.

You can also show 18 with base-ten blocks (1 ten rod and 8 small cubes), with digits (18) or with words (eighteen). They all show the same number!

Base-ten blocks: 1 ten rod and 8 ones cubes.

How do we use numbers?

We use numbers in many different ways every day:

To tell how many: "There are 24 children in my class."
To tell order: "I was 3rd in line."
To measure: "My pencil is 15 centimetres long." "It's 12 days until Canada Day."
As a name or label: a hockey player's jersey number, a bus number, or the number on your house. These numbers tell us which one, not how many.
For money: "This toy costs 20 dollars."
For time: "I go to bed at 7 o'clock."

Worked example

What does the number tell us?

Maya's hockey jersey has the number 19 on it. Does that mean there are 19 players on her team?

Think about what the number is used for.
A jersey number is a label. It helps people know which player is which.
It does not tell us how many players there are.

No. The number 19 is a name for Maya on the ice, not a count.

Just for fun

Why did the two 4s skip lunch?

They already 8 (ate)!

Hands-on activity

Number hunt

You need: paper and a pencil.

Walk around your home (or outside with a grown-up) and look for numbers up to 50.
Write each number you find. Look on clocks, calendars, food boxes, books, remote controls, doors and signs.
Beside each number, draw a picture of where you found it.
Talk about each number: Is it telling how many? Is it a measurement? Is it a label?
Choose your favourite number and show it in three ways: with a drawing, with tally marks and with words.

Your turn!

Write forty-two using digits.

Write 15 in words.

Write 33 in words.

A ten frame is full and 4 more dots are on a second ten frame. What number is shown?

Which number is twenty-nine: 92 or 29?

Draw tally marks for 12.

The calendar says it is the 28th of the month. Is the number telling how many, order or a label?

Write the number that is shown by 4 ten rods and 0 cubes.

More practice: warm-up

Write nineteen using digits.

Write 40 in words.

Count the teddy bears. Write the number with digits and with a word.

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True or false: 14 and 41 are the same number.

Write fifty using digits.

More practice: on your own

Draw tally marks for 23.

Two ten frames are full and a third ten frame has 6 dots. What number is shown? Write it with digits and in words.

Which number is forty-eight: 84, 48 or 408?

Count the maple leaves. Write the number with digits and in words.

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"Our pumpkin is 30 centimetres tall." Is the number 30 telling how many, order, a measurement or a label?

Challenge

Find the mistake! Tom wrote thirty-five as 305. What did he do wrong? What is the right way?

Show 32 in three different ways.

A school bus has the number 24 on its side. There are 24 children riding the bus. Do both 24s mean the same thing? Explain.

Check your understanding

Quiz

Which number is thirty-one?

How do you write 17 in words?

Which picture shows 23?

Sam's house number is 45. What does the number tell us?

How do you write forty-four with digits?

Which tally marks show 21?

For parents and teachers

What your child is learning: to read and write numbers to 50 in digits and in words, to show them with materials (ten frames, tally marks, base-ten blocks, number lines), and to notice how numbers are used in daily life (counting, ordering, measuring and labelling).

Common mistakes and how to help:

Reversing digits (writing 31 for 13). Teen numbers are said "backward": we hear the ones (four-teen) before the ten. Build the number with 1 ten and the ones so your child sees which digit is the ten.
Writing numbers the way they sound, like 205 for twenty-five. Remind your child that twenty means 2 tens and fills the first place; numbers to 50 have at most two digits.
Backward digits (a reversed 3, 7 or 9). This is very common at age 6 and usually fixes itself with practice. Show the correct form without fuss.
Spelling forty (not fourty) and eleven/twelve. Keep a number word chart on the fridge.

Everyday practice: read house numbers, prices and page numbers together. Ask "Is that number telling how many, or is it a name?"

Math talk questions: "How else could you show that number?" "How are 14 and 41 different?"