Mathematics / Year 3 / Algebra

Curriculum content descriptions

extend and apply knowledge of addition and subtraction facts to 20 to develop efficient mental strategies for computation with larger numbers without a calculator (AC9M3A02)

Elaborations
  • partitioning using materials and part-part-whole diagrams to develop subtraction facts related to addition facts, such as \(8 + 7 = 15\) therefore, \(15 \space–\space 7 = 8\) and \(15\space – \space 8 = 7\)
  • using partitioning to develop and record facts systematically; for example, “How many ways can \(12\) monkeys be spread among \(2\) trees?”, \(12 = 12 + 0\), \(12 = 11 + 1\), \(12 = 10 + 2\), \(12 = 9 + 3\), …; explaining how they know they have found all possible partitions
  • understanding basic addition and related subtraction facts and using extensions to these facts; for example, \(6 + 6 = 12, 16 + 6 = 22, 6 + 7 = 13, 16 + 7 = 23\), and \(60 + 60 = 120, 600 + 600 = 1200\)
General capabilities
  • Critical and creative thinking Critical and Creative Thinking
  • Numeracy Numeracy
ScOT terms

Mental arithmetic,  Associativity,  Commutativity,  Generalisation,  Subtraction,  Addition

Interactive

Goat Crashers (Mental calculations with unconditional probability) - ABC Education

Using your knowledge of different operations, join the Pig Posse to help kick them out before they eat everything. Or join the goats and move on in! Mathematical ideas and strategies this game supports: addition and subtraction with 1–30; multiples of 2, 3, 4, 5, 6, 8 and 10; dividing by 3, 4, 5, 6, 8 and 10.

Interactive

Goat Grommets (Mental computation and dependent probability) - ABC Education

As a team, you'll need to use your understanding of probability to decide which waves your surfer should catch — or when to play it safe and head in. Use mental addition to calculate your score. Enjoy the surf but watch out for the shark pig! Mathematical ideas and strategies this game supports: the probability of an occurrence ...

Interactive

Thundergoats (Combinations for ten) - ABC Education

As a team, use your knowledge of different strategies to find the total number of Thundergoats as efficiently as possible (e.g. use combinations for ten). Mathematical ideas and strategies this game supports: noticing how items are organised can help you work out their total (subitising). There are many ways to add and ...

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Subtraction Year 3 & 4 - Calculate

This activity is designed to encourage students to develop and explain different strategies to solve subtraction problems.

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Addition Year 3 - Calculate

This activity is designed to see if students are able to apply their addition strategies in order to find the total of their collection of cards. Often students will have a method for adding two numbers, but when asked to add a list of numbers they revert to less efficient methods.

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Subtraction Strategies - Calculate

This game gives students opportunities to practice subtraction skills and to learn subtraction strategies, including the jump strategy, the split (or partition) strategy, compensation and the count-up to strategy (sometimes called the Shopkeeper’s method).

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Addition and Subtraction - Calculate

This game focuses on addition, subtraction and estimation. It can be played many times as the totals will often be different and the focus of the mathematics can change. There is a video included to help with how to play the game.

Interactive

Goat to bed (Partitioning twenty) - ABC Education

Some naughty little goats should be in bed, but they are still up and playing games! You will need to choose teams, then use your strategies (such as combinations for 20) to decide who wins: baby goats or babysitter! Mathematical ideas and strategies this game supports: numbers can be partitioned in many ways; there are ...

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Pattern & Algebra Year 3 - Calculate

The focus of this activity is to discover if students can use numbers to describe a pattern created with objects. We want to encourage students to record what they know about the pattern in a table and then use this information to help predict future terms and identify the rule or function for the pattern. At this stage, ...

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Salute - Calculate

This game gives students opportunities to practise addition and subtraction strategies and develop algebraic thinking by finding unknown values in additive equations.

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Park Ranger Problem Solving: An ‘Addition & Subtraction’ Rich Task for Years 3–4 - Calculate

The aim of this task is to provide a rich, contextual activity through which students can begin to explore the addition and subtraction of one- and two-digit of numbers in everyday contexts.

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Addition Strategies - Calculate

Regular practise of addition facts can help children build their confidence in maths.

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reSolve: Algebra: Number Sequences

This sequence of lessons aims to build students' algebraic thinking through explorations of additive number patterns. Students are challenged to solve problems to generate patterns, explore strategies for addition and subtraction and apply their skills to constructing their own new patterns.The lessons are outlined in detail ...

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reSolve: Addition: Chess - The Rook

This lesson engages students in investigating place value and the addition and subtraction of numbers by exploring computation on the number chart. Students analyse the moves of a rook chess piece and how the value of the numbers change as he moves. This builds into an exploration of how the number chart can be used as ...

Interactive

The difference bar: generate easy subtractions

Learn how to split up numbers in your head. Use a linear partitioning tool to help find the difference between pairs of two-digit numbers such as 25 and 34. In these examples, the difference is always less than ten. Split the numbers into parts that are easy to work with, work out each part and then solve the original calculation.

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reSolve: Multiplication - Domino Arrays

This sequence of two lessons explores multiplicative thinking through the use of arrays where all the parts of the array are not visible. The sequence encourages students to find the total number of items in an array by multiplication rather than counting by ones or skip counting. Connections between area, arrays and multiplication ...

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reSolve: Measurement - Jump!

In this sequence of two lessons, students investigate how far they can jump and explore the jumping distance of a range of animals. Students first estimate the distance they can jump, then undertake an investigation by jumping using a range of techniques. Class data is recorded and displayed and students compare their jumping ...

Video

What is a fractal?

Do you know what a fractal is? Basically, fractals are never-ending patterns created by repeated mathematical equations. In this clip, Yuliya, a student at MIT (in the USA) describes the properties of fractals and shows you where they can be found in technology and nature. Have a good look at the world around you and see ...

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BTN: What is an abacus?

An abacus is a tool that helps people solve maths problems. Why might some people still use, and encourage the use of, an abacus when there are more contemporary tools like calculators?

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Fractions in the real world

How many quarters make up a whole? Watch this video to find out how else you can represent 2/4 and how to add up quarters to make a whole.