AC9M2A01_E1
Create a pattern with materials, write the associated number sequence and describe the rule so another person can reproduce the pattern using different materials.
Chapter 7 • AC9M2A01
Help your child recognise, describe and create additive patterns that increase or decrease by a constant amount. This parent-friendly guide explains number patterns, growing shape patterns, missing elements, digital patterns and pattern rules before children complete the printable activities aligned with AC9M2A01.
In this Year 2 unit, children explore additive patterns that increase or decrease by the same amount each time.
An increasing additive pattern may be:
3, 5, 7, 9, 11
The rule is: start at 3 and add 2 each time.
A decreasing additive pattern may be:
20, 17, 14, 11, 8
The rule is: start at 20 and subtract 3 each time.
Children also create patterns with objects and shapes, record the matching number sequences, identify missing elements and explain the rule clearly enough for another person to reproduce the pattern.
These activities support Australian Curriculum Version 9.0 content descriptor AC9M2A01 and its associated elaborations.
Recognise, describe and create additive patterns that increase or decrease by a constant amount, using numbers, shapes and objects, and identify missing elements in the pattern.
Create a pattern with materials, write the associated number sequence and describe the rule so another person can reproduce the pattern using different materials.
Recognise additive patterns in the built environment, including repeated quantities such as windows in train carriages or wheels on cars, and record the results in diagrams or tables.
Recognise the constant amount being added or subtracted and use the rule to identify missing elements in an additive sequence.
Use dynamic geometric software or a generative artificial intelligence tool to create patterns that increase or decrease by a constant amount and discuss the instructions used to generate the pattern.
Recognise additive patterns in the environment on Country and Place and in First Nations Australian material culture, and represent them using drawings, coloured counters and numbers.
The most important part of an additive pattern is the constant change between consecutive elements.
Children should learn to describe both:
For example, the sequence:
5, 9, 13, 17, 21
can be described as:
Start at 5 and add 4 each time.
Children will learn to:
I can recognise an additive pattern.
I can identify whether a pattern is increasing or decreasing.
I can identify the starting number.
I can find the constant amount being added.
I can find the constant amount being subtracted.
I can continue a pattern correctly.
I can find missing numbers in a pattern.
I can create a pattern using objects or shapes.
I can write the number sequence represented by a pattern.
I can describe a pattern rule clearly.
I can record a pattern in a table.
I can explain how I know my answer is correct.
Teachers introduce additive patterns through physical materials and visual models before moving to number sequences and missing elements.
At home, follow this sequence: build it, count it, record it, describe it and extend it.
Use counters, blocks, matchsticks, toothpicks or craft sticks to create a pattern that grows by the same amount each time.
For example, create connected triangles:
The associated number sequence is:
3, 5, 7, 9
The rule is: start at 3 and add 2 each time.
After building each stage, count the total number of materials used and write the result underneath.
Encourage your child to connect each number to a particular stage of the pattern.
“What changed from one stage to the next, and how many objects were added?”
The starting number is the first number shown in the sequence.
In:
4, 7, 10, 13, 16
the starting number is 4.
Children should include the starting number when describing the complete pattern rule.
Compare each number with the number immediately before it.
For example:
6, 10, 14, 18, 22
Each number is 4 greater than the previous number, so the constant change is:
add 4.
Check more than one pair of numbers. The change must remain the same throughout an additive pattern.
A complete rule should state:
For:
12, 17, 22, 27, 32
the rule is:
Start at 12 and add 5 each time.
Saying only “add 5” describes the change but not the complete sequence.
Use a collection of objects and remove the same number at each stage.
For example:
25, 21, 17, 13, 9
The rule is:
Start at 25 and subtract 4 each time.
Ask your child whether the numbers are becoming larger or smaller.
Begin with a sequence that contains one missing number:
7, 10, __, 16, 19
The rule is add 3, so the missing number is 13.
Encourage your child to check the pattern on both sides of the missing position.
Missing numbers may appear at the beginning rather than in the middle.
For example:
__, 14, 18, 22, 26
Since the rule is add 4, work backwards by subtracting 4:
14 − 4 = 10
The missing number is 10.
Once the child understands one missing element, use patterns with several gaps.
For example:
30, __, 24, __, 18
The constant rule is subtract 3:
30, 27, 24, 21, 18
Ask your child to create one growing pattern with blocks and then describe it so another person can reproduce the same number sequence using counters.
This helps children understand that the mathematical rule stays the same even when the materials change.
“Start with 2 counters and add 3 counters at every new stage.”
Tables help children connect the stage number with the total number of objects.
| Number of Cars | Number of Wheels |
|---|---|
| 1 | 4 |
| 2 | 8 |
| 3 | 12 |
| 4 | 16 |
The number of wheels increases by 4 for every additional car.
Look for repeated quantities in buildings, vehicles and other constructed objects.
Examples include:
Ask your child to record the pattern using a drawing, number sequence or table.
Suppose each train carriage has 6 windows.
Record:
The number sequence is:
6, 12, 18, 24
The rule is: start at 6 and add 6 each time.
A shape pattern may grow by adding the same number of shapes at every stage.
For example:
The number sequence is:
2, 5, 8, 11
The visual arrangement may change, but the total increases by 3 each time.
A digital geometry tool can be used to copy, move and add shapes to create a growing pattern.
Ask your child to:
Children may write instructions for a digital tool to generate a geometric pattern.
A simple instruction might be:
“Create four stages of a pattern. Start with 3 circles and add 2 circles at every new stage.”
After viewing the result, ask:
Children should use age-appropriate digital tools with adult supervision and should not enter personal information.
A digital result may not follow the intended rule.
For example:
3, 5, 8, 10
This is not a constant add-2 pattern because the change from 5 to 8 is 3.
Ask your child to identify the error and rewrite the instruction more precisely.
Children can observe repeated and additive arrangements in the environment on Country and Place.
These may be represented using:
Use local or trusted First Nations educational resources when discussing cultural examples and keep the mathematical activity connected to its original context.
Not every pattern is an additive pattern.
For example:
2, 4, 8, 16
does not increase by a constant added amount.
Ask your child to calculate or describe the change between each pair of terms. If the change is not constant, the sequence is not an additive pattern.
Once the rule is known, children can use it to predict later elements.
For:
8, 13, 18, 23
the next two numbers are 28 and 33 because 5 is added each time.
Check the change between several consecutive terms. A constant rule must work throughout the entire sequence.
Ask what is added or subtracted each time. A complete rule needs both the starting number and the constant change.
“Add 3” is not enough to reproduce a unique sequence. Add the starting number to the description.
Record the difference between each pair of consecutive numbers and compare the results.
Ask whether the numbers are becoming larger or smaller and identify the direction of the change.
Identify the rule first and apply it from the number before the missing position. Then check using the number after it.
Mark or separate the new shapes added at each stage so the constant growth is visible.
Repeating patterns repeat a fixed unit. Additive patterns change in quantity by a constant amount.
Count the number of objects at every stage and compare the numerical differences.
Count and verify each stage. Digital tools can produce results that do not match the intended instruction.
Begin with a small group of counters and add the same number at every stage.
Record the total after each addition.
Focus: Recognising constant growth.
Build connected triangles or squares and count the number of sticks used at each stage.
Write the number sequence and describe the rule.
Focus: AC9M2A01_E1.
Write rules such as “start at 6 and add 4” on cards.
Ask your child to create the first five numbers in each sequence.
Focus: Translating rules into sequences.
Write increasing and decreasing sequences with one or more missing numbers.
Ask your child to identify the rule before filling the gaps.
Focus: AC9M2A01_E3.
One person describes a pattern rule while the other person builds the pattern using different materials.
Check whether the instructions were clear enough.
Focus: Mathematical communication.
Record the number of wheels for 1 car, 2 cars, 3 cars and more.
Display the results in a table and describe the rule.
Focus: Built-environment patterns.
Choose a fixed number of windows for each carriage and calculate the total for several carriages.
Record the pattern using a diagram, table and number sequence.
Focus: AC9M2A01_E2.
Build a tall tower and remove the same number of blocks at each stage.
Record and describe the decreasing number pattern.
Focus: Constant subtraction.
Write an instruction for an age-appropriate digital tool to create a growing shape pattern.
Count each stage and check whether the output follows the rule.
Focus: AC9M2A01_E4.
Look for repeated quantities and growing arrangements in buildings, vehicles and the local environment.
Draw one example and record the associated number pattern.
Focus: Environmental pattern recognition.
The pattern starts at _____.
The pattern is increasing by _____.
The pattern is decreasing by _____.
The complete rule is _____.
I know the rule is constant because _____.
The next element is _____ because _____.
The missing number is _____.
I checked the missing number by _____.
At each stage, _____ objects are added.
At each stage, _____ objects are removed.
The object pattern represents the sequence _____.
I recorded the pattern in a table by _____.
My instructions are _____.
The digital output followed the rule because _____.
The digital output needs to be corrected because _____.
This is an additive pattern because _____.
Use these questions to check whether your child understands the main ideas.
A child shows secure understanding when they can identify the constant change, continue and complete a sequence, create a matching visual pattern and communicate the complete rule.
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Additive pattern understanding grows when children build, record and explain patterns using several representations.
Use this simple routine:
Children who need additional support can revisit these earlier counting and pattern topics.
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