Mathematics / Year 4 / Algebra

Curriculum content descriptions

find unknown values in numerical equations involving addition and subtraction, using the properties of numbers and operations (AC9M4A01)

Elaborations
  • demonstrating the commutative properties of addition using materials, diagrams and number lines; for example, using number lines to demonstrate that \(5 + 2 = 2 + 5\), demonstrating that \(2 + 2 + 3 = 7\) and \(2 + 3 + 2 = 7\) and \(3 + 2 + 2 = 7\)
  • using balance scales and informal uniform units to create addition or subtraction number sentences showing equivalence, such as \(7 + 8 = 6 + 9\), and to find unknowns in equivalent number sentences, such as \(6 + 8 = \square + 10\)
  • using relational thinking and knowledge of equivalent number sentences to explain whether equations involving addition or subtraction are true; for example, explaining that \(27 \space– \space 14 = 17\space – \space4\) is true and using a number line to show the common difference is \(13\)
  • using part-part-whole diagrams or bar models to recognise and explain the inverse relationship between addition and subtraction, using this to make calculations easier; for example, solving \(27 + \square = 63\) using subtraction, \(\square = 63\space – \space27\)
General capabilities
  • Critical and creative thinking Critical and Creative Thinking
  • Numeracy Numeracy
ScOT terms

Associativity,  Mathematical expressions,  Subtraction,  Addition

Online

reSolve: Algebra: Chess - The King

This lesson aims to build students' algebraic reasoning and understanding of number as they explore computation on the number chart. Students explore the moves of a king chess piece and how the value of the numbers change as he moves. This builds into an algebraic exploration of equivalent values that can be found on the ...

Online

reSolve: Algebra: Odds and Evens

This sequence of two lessons focuses on developing students' understanding of the properties of odd and even numbers. Students explore the results of adding and subtracting odd and even numbers and use these results to make generalisations. They then apply this generalisation to solve problems and to explore patterns. The ...

Online

reSolve: Algebra: Triangle Inequality

This sequence of two lessons explores the triangle inequality theorem. Students are challenged to construct triangles with a given number of matchsticks, explore and record what combinations of sticks can create valid triangles and represent their findings using mathematical expressions. Each lesson is outlined in detail ...

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Sites2See: Patterns and Algebra

Selected links to a range of interactive online resources for the study of patterns and algebra in Foundation to Year 6 Mathematics.

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Paying It Forward Years 3-4

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Find unknown values: Year 4 – planning tool

This planning resource for Year 4 is for the topic of Find unknown values. Students further develop their algebraic thinking and strategies to find missing or unknown numbers in addition and subtraction related problems.

Downloadable

Algebra: Foundation to Year 9

This comprehensive resource describes the progression of algebra-related ideas and algebraic thinking. The resource demonstrates examples of relevant teaching strategies, investigations, activity plans and connected concepts in algebra including teaching and cultural implications.

Online

reSolve: Place Value: Cartoon Counting

This lesson engages students in investigating place value by considering a counting system using base 8. Students are challenged to imagine how place value would work in a cartoon world where everyone only had eight fingers. They engage in activities with counting blocks, representing numbers in base 10 and in base 8 and ...

Online

reSolve: Multiplication - Cartesian Product

This sequence of two lessons introduces the idea of multiplication as a Cartesian product, using the language of 'for each'. Students learn to use a tree diagram to find the number of possible combinations that can be made in an animal mix and match book. They learn how a simpler problem can be used to help solve a larger, ...

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 ...

Video

Fun with fractals

Do you know how to recognise a fractal? Watch this video to find out! What are the examples given of fractals found in nature? Can you think of any others? Why not have a go at doing your own drawing of the Sierpinski Triangle?

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What is a quarter?

What is a quarter? You get quarters when you divide a whole into four equal parts. Each one of these four parts is a quarter. Watch this great explainer produced by Monique in collaboration with ABC Splash and see how she explains quarters.

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MathXplosion, Ep 2: Double that number

Explore an age-old multiplication method that repeatedly doubles numbers to get a product. Learn how this ancient method of multiplication is similar to that used by modern computers.

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Mixed Up Maths, Ep 1: Monumental measurement mess ups

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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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Numbers Count: What are factors?

What are factors? Watch as the jelly babies in this clip show you! What are the factors of 12? How many factors does the number 11 have? Try explaining to a friend what a prime number is.

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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.

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MathXplosion, Ep 33: On the grid

Explore graphs, grids and mapping with a focus on reading and writing location data using coordinate geometry. Grids and maps illustrate the concepts of parallel/perpendicular lines (axes or labelled number lines), ordered pairs and intersection points.

Video

Musical fractions

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Interactive

Wishball: hundredths

Test your understanding of decimal place value with numbers that include hundredths. Receive a starting number, such as 46.87, and work towards turning it into a target number, such as 85.32. Spin a random digit, choose its decimal place value and decide whether to add or subtract the random digit from your starting number. ...