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Counting, comparing, ordering and estimating

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visibility 57update 2 months agobookmarkshare

🎯 In this topic you will

Count objects accurately up to 20.
Compare and order quantities correctly.
Estimate quantities and then count to check accuracy.

🧠 Key Words

digit
number line

Show Definitions

digit: A single symbol used to represent numbers, such as 0–9 in the base-ten number system.
number line: A straight line with numbers placed in order at equal intervals, used to represent and compare values.

🔢 Understanding What Numbers Mean

It is important to understand what each of the numbers means.

🧮 Using Numbers to Make Choices

You can use what you know about numbers to decide which pack of marbles to buy.

📘 Worked example

How many?

Answer:

$10 + 4 = 14$

You do not need to count from 1 because the full ten frame already shows 10 apples.

Count on from 10: 10, 11, 12, 13, 14.

So there are 14 apples altogether.

❓ EXERCISES

1. How many objects are there? Write each number. Use place value cards to help you.

👀 Show answer

The first ten-frame shows $10$ footballs. The second frame shows $8$ footballs, so the total is $18$. The pens show $10$ coloured pens and $5$ extra pens, making $15$ pens.

2. Draw the correct number of counters.

👀 Show answer

You should draw $12$ counters. Fill one full ten-frame with $10$ counters and then add $2$ more in the second frame.

3. This is a bead string. The first $10$ beads are red. The next $10$ beads are white. How many beads are there?

a. How many beads can you see on each bead string?

👀 Show answer

There are $20$ beads in total because $10$ red beads plus $10$ white beads equals $20$. Count the visible beads on each string to confirm.

📘 Worked example

Are there more red cars or more yellow cars?

Answer:

There are more yellow cars than red cars.

$15$ is greater than $13$.

Compare the numbers on the number line.

$15$ is further along the number line than $13$, so it is greater.

We use greater when comparing numbers.

❓ EXERCISES

4. Are there more marbles or stickers?

There are ______ marbles.

There are more ______ than ______.

There are ______ stickers.

______ is greater than ______.

👀 Show answer

There are $12$ marbles. There are more stickers than marbles. There are $15$ stickers. $15$ is greater than $12$.

5. Are there fewer lollipops or children?

There are ______ lollipops.

There are fewer ______ than ______.

There are ______ children.

______ is less than ______.

Can every child have a lollipop? ______

👀 Show answer

There are $10$ lollipops. There are fewer lollipops than children. There are $11$ children. $10$ is less than $11$. No, every child cannot have a lollipop.

6. Estimate how many children. Estimate how many sweets. Can every child have a sweet? Count the children and the sweets to see if you were correct.

👀 Show answer

There are $10$ children and $9$ sweets. No, every child cannot have a sweet because there are fewer sweets than children.

7. Write less or greater to complete the sentences.

a. $19$ is ______ than $16$.

b. $16$ is ______ than $19$.

c. $11$ is ______ than $15$.

d. $15$ is ______ than $11$.

👀 Show answer

a. greater
b. less
c. less
d. greater

8. Mark $3$ and $18$ on the number line.

👀 Show answer

Place one mark at $3$ and another mark at $18$ on the number line.

🧠 Think like a Mathematician

Let’s investigate

Method:

Choose any $3$ numbers between $10$ and $20$.
Put them in order from smallest to greatest.
Now look at your numbers on the number line. Write down what you notice.
Repeat with $3$ new numbers.

Follow-up Questions:

1. What do you notice about the order of numbers as you move along the number line?

2. How can you tell which of your three numbers is the greatest without counting from $1$?

3. If two numbers are close together on the number line, what does that tell you about the difference between them?

👀 show answer

1: Numbers get larger as you move to the right on the number line, and they get smaller as you move to the left.
2: The greatest number is the one furthest to the right on the number line.
3: If two numbers are close together, the difference between them is small (for example, $14$ and $15$ differ by $1$).

🗣️ Talking About Your Investigation

Talk with your partner about your investigation. Answer all the questions in the diagram.

❓ EXERCISES

9. Write your estimate in the number box. Then count the butterflies and the dragonflies and write how many.

👀 Show answer

Accept reasonable estimates. Counting carefully shows there are $12$ butterflies and $16$ dragonflies (answers may vary slightly depending on counting method).

📘 What we've learned

We learned how to count objects accurately up to $20$.
We practiced comparing quantities to decide which number is greater or less.
We used number lines to understand that numbers further to the right are greater.
We estimated quantities and then counted to check our answers.
We used place value knowledge such as $10 + 4 = 14$ to find totals efficiently.

Counting, comparing, ordering and estimating

🎯 In this topic you will

🧠 Key Words

🔢 Understanding What Numbers Mean

🧮 Using Numbers to Make Choices

❓ EXERCISES

❓ EXERCISES

🧠 Think like a Mathematician

🗣️ Talking About Your Investigation

❓ EXERCISES

📘 What we've learned

Related Past Papers

Related Tutorials

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