AC9M2A03_E1
Recognise and relate the terms double, twice and multiply by 2, and halve and divide by 2, using physical and virtual materials, hundreds charts and related multiplication facts.
Chapter 9 • AC9M2A03
Build confident recall of multiplication and division facts for twos through doubling, halving, the 2 times table and related division facts. This parent-friendly guide explains the strategies children use before completing the printable activities aligned with Australian Curriculum code AC9M2A03.
In this unit, children develop fluency with multiplication facts for twos and use doubling and halving to understand related division facts.
Children connect the terms:
For example:
Double 6 is 12.
This can also be represented as:
2 × 6 = 12
The related division fact is:
12 ÷ 2 = 6
Children use counters, connecting cubes, number lines, hundreds charts, virtual manipulatives and games to develop accurate and efficient recall.
These activities support Australian Curriculum Version 9.0 content descriptor AC9M2A03 and its associated elaborations.
Recall and demonstrate proficiency with multiplication facts for twos; extend and apply facts to develop related division facts using doubling and halving.
Recognise and relate the terms double, twice and multiply by 2, and halve and divide by 2, using physical and virtual materials, hundreds charts and related multiplication facts.
Double and halve collections to develop fluency with multiplication and division facts for twos, leading to accurate recall.
Use physical or virtual manipulatives to develop an understanding of doubles and near doubles and extend known doubling facts to nearby numbers.
Develop fluency with doubling and halving numbers within 20 through materials, virtual tools and doubling and halving games.
Doubling combines two equal quantities. Halving separates a quantity into two equal parts.
For example:
Double 7 is 14.
Therefore:
Half of 14 is 7.
This relationship helps children connect multiplication and division rather than learning the facts as unrelated calculations.
Children will learn to:
I can explain what double means.
I can explain what half means.
I can connect twice with multiply by 2.
I can connect halve with divide by 2.
I can double a collection.
I can halve an even collection.
I can recall multiplication facts for twos.
I can write related division facts.
I can use a known double to find another double.
I can identify doubles on a hundreds chart.
I can double and halve numbers within 20.
I can explain the strategy I used.
Teachers introduce doubling and halving through equal groups and practical materials before expecting rapid recall of number facts.
At home, follow this sequence: make it, share it, record it, connect it and recall it.
Use counters, blocks or household objects to make groups of two.
Ask your child to make:
Count the totals:
2, 4, 6, 8, 10
“Three groups of two contain six objects altogether.”
Doubling means making two equal copies of a quantity and combining them.
To double 4:
4 + 4 = 8
Therefore:
Double 4 is 8.
Use several phrases for the same relationship.
These statements have the same meaning:
Regularly changing the language helps children recognise the relationship in different types of questions.
Halving means separating a quantity into two equal parts.
To halve 12:
Each group contains 6.
Therefore:
Half of 12 is 6.
These statements have the same meaning:
Use physical sharing so children understand that the two groups must be equal.
Doubling and halving undo each other.
If:
Double 8 is 16
then:
Half of 16 is 8.
Ask children to write both facts together:
2 × 8 = 16
16 ÷ 2 = 8
Build each fact with materials before recording it.
| Groups of Two | Total |
|---|---|
| 1 × 2 | 2 |
| 2 × 2 | 4 |
| 3 × 2 | 6 |
| 4 × 2 | 8 |
| 5 × 2 | 10 |
| 6 × 2 | 12 |
| 7 × 2 | 14 |
| 8 × 2 | 16 |
| 9 × 2 | 18 |
| 10 × 2 | 20 |
Skip counting supports the two times table when it is connected to equal groups.
Point to each pair while counting:
2, 4, 6, 8, 10, 12, 14, 16, 18, 20
Each count represents one additional group of two.
Do not rely on chanting the sequence alone. Ask how many groups have been counted and what the total represents.
Colour the multiples of two on a hundreds chart.
Children should notice that:
Ask your child to choose an even number and identify its half.
Children may use the commutative relationship to recognise:
8 groups of 2
and:
2 groups of 8
both have a total of 16.
This can be recorded as:
8 × 2 = 16
and:
2 × 8 = 16
Give your child a collection of objects and ask them to make a second identical collection.
For a collection of 7:
7 + 7 = 14
Record the doubling fact and related multiplication fact.
Begin with an even collection and deal the objects one at a time between two groups.
For 18 objects:
each group receives 9.
Record:
18 ÷ 2 = 9
and:
Half of 18 is 9.
A known double can help children find a nearby double.
If:
Double 5 is 10
then double 6 is two more because both equal groups increased by one:
10 + 2 = 12
Therefore:
Double 6 is 12.
Double 4 is two less than double 5 because both groups contain one fewer object.
Double 5 = 10
10 − 2 = 8
Therefore:
Double 4 is 8.
Near doubles involve two quantities that differ by one.
For:
6 + 7
use:
Double 6 = 12
and add one more:
12 + 1 = 13
Physical or virtual cube towers can make this difference visible.
Use a double and its total to write related multiplication and division facts.
For 7 and 14:
The key Year 2 division connection in this unit is halving:
14 ÷ 2 = 7
Practise doubling numbers from 0 to 10 and halving even numbers from 0 to 20.
Useful pairs include:
Roll a die and choose whether to double or halve the number to move towards a target.
For example, the target is 12.
Use only whole-number halves when working at this level.
Even numbers can be separated into two equal whole-number groups.
Use materials to compare:
This helps children recognise why the halving facts in this unit use even starting numbers.
Ask children to explain how they found the answer rather than giving only a number.
Useful explanations include:
Double means two equal copies of a quantity. Build two matching groups to show the difference.
Halving means sharing a quantity into two equal groups, not removing two objects.
Deal objects one at a time between two groups and check that both groups contain the same number.
Ask separately: “How many groups are there?” and “How many objects are in each group?”
Ask whether the child recognises two equal collections and knows the matching double fact.
Use objects, arrays or drawings so each fact represents a known number of equal groups.
Record multiplication and related division facts beside each other.
When moving from double 5 to double 6, both equal groups increase by one, so the total increases by two.
Use materials to show that an odd collection leaves one object when divided into two equal whole-number groups.
Focus first on accurate representations, efficient strategies and clear explanations.
Make a collection of counters and ask your child to create an identical collection.
Combine the collections and record the double fact.
Focus: Understanding doubling.
Give your child an even collection and ask them to share it equally between two plates or containers.
Record the related division fact.
Focus: Understanding halving.
Make groups of two using buttons, blocks or toy animals.
Count the groups and write the matching multiplication facts.
Focus: Multiplication facts for twos.
Colour multiples of two on a hundreds chart and describe the patterns in the coloured numbers.
Choose numbers within 20 and identify their halves.
Focus: AC9M2A03_E1.
Write numbers from 1 to 20 on cards.
Ask your child to double numbers to 10 and halve even numbers to 20.
Focus: Fluency within 20.
Give a known double such as double 5 and ask how it can help find double 4 or double 6.
Use cube towers to explain the difference.
Focus: AC9M2A03_E3.
Roll a die and choose whether to double or halve the number.
Players explain their choice and record the result.
Focus: AC9M2A03_E4.
Match a multiplication fact with its related halving fact.
Example: 2 × 9 = 18 matches 18 ÷ 2 = 9.
Focus: Related multiplication and division facts.
Sort number cards into numbers that can and cannot be halved into two equal whole-number groups.
Check each number using counters.
Focus: Even numbers and equal halving.
Choose a target number within 20 and use doubling or halving moves to reach it.
Record each move and explain the strategy.
Focus: Flexible doubling and halving.
Double _____ is _____.
Twice _____ is _____.
Two groups of _____ make _____.
The multiplication fact is _____.
Half of _____ is _____.
I divided _____ into two equal groups of _____.
The related division fact is _____.
I used the known double _____.
Double _____ is two more than double _____.
I know the groups are equal because _____.
This number can be halved because _____.
This number cannot be halved into whole numbers because _____.
I found the total by skip counting _____.
Doubling and halving are connected because _____.
The pattern on the hundreds chart is _____.
I checked my answer by _____.
Use these questions to check whether your child understands the main ideas.
A child shows secure understanding when they can recall or efficiently derive multiplication facts for twos, find related division facts and explain the connection between doubling and halving.
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Multiplication and division fact fluency develops when children understand equal groups and recognise that doubling and halving are connected.
Use this simple routine:
Children who need additional support can revisit these earlier grouping, sharing, skip-counting and number-fact topics.
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