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# Mathematics / Year 3 / Number and Algebra / Number and place value

Curriculum content descriptions

Recall addition facts for single-digit numbers and related subtraction facts to develop increasingly efficient mental strategies for computation (ACMNA055)

Elaborations
• recognising that certain single-digit number combinations always result in the same answer for addition and subtraction, and using this knowledge for addition and subtraction of larger numbers
• combining knowledge of addition and subtraction facts and partitioning to aid computation (for example 57 + 19 = 57 + 20 – 1)
General capabilities
• Numeracy Numeracy
ScOT terms

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Year level 3-4
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Learning area Mathematics

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### Sites2See – number for primary

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

### 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.

### The take-away bar: generate hard subtractions

Solve subtractions such as 87-29. Use a linear partitioning tool to help solve randomly generated subtractions. Learn strategies to do complex arithmetic in your head. Split a subtraction into parts that are easy to work with, work out each part and then solve the original calculation. This learning object is one in a series ...

Solve addition sums such as 43+29. Use a linear partitioning tool to help solve your own addition sums. Learn strategies to do complex addition sums in your head. Split a sum into parts that are easy to work with, work out each part and then solve the original calculation. This learning object is one in a series of five objects.

### The take-away bar: generate easy subtractions

Solve subtractions such as 28-9. Use a linear partitioning tool to help solve randomly generated subtractions. Learn strategies to do complex arithmetic in your head. Split a subtraction into parts that are easy to work with, work out each part and then solve the original calculation. This learning object is one in a series ...

Solve addition sums such as 58+9. Use a linear partitioning tool to help solve your own addition sums. Learn strategies to do complex sums in your head. Split a sum into parts that are easy to work with, work out each part and then solve the original calculation. This learning object is one in a series of five objects.

### The difference bar: make your own easy subtractions

Learn how to split up numbers in your head. Use a linear partitioning tool to help find the difference between pairs of numbers such as 8 and 64. Choose your own pairs of numbers (a single-digit number and a two-digit number). Split the numbers into parts that are easy to work with, work out each part and then solve the ...

### Mental computation: basic facts - addition and subtraction

This is a teacher resource that is part of a wider series; it develops a structured strategies-based approach to mental computation of the 242 basic mathematics facts at primary level. The resource provides 13 stimulating classroom activities that encourage students to use a wide variety of mental-computation strategies. ...

### The take-away bar: make your own hard subtractions

Solve subtractions such as 93-47. Use a linear partitioning tool to help solve your own subtractions. Learn strategies to do complex arithmetic in your head. Split a subtraction into parts that are easy to work with, work out each part and then solve the original calculation. This learning object is one in a series of five ...

### The part-adder: generate easy sums

Solve addition sums such as 28+9. Use a linear partitioning tool to help solve randomly generated addition sums. Learn strategies to do complex sums in your head. Split a sum into parts that are easy to work with, work out each part, then solve the original calculation. This learning object is one in a series of five objects.

### The take-away bar: make your own easy subtractions

Solve subtractions such as 58-9. Use a linear partitioning tool to help solve your own subtractions. Learn strategies to do complex arithmetic in your head. Split a subtraction into parts that are easy to work with, work out each part and then solve the original calculation. This learning object is one in a series of five objects.

### MoneySmart: Sal's secret

This is a year 3 mathematics unit of work about saving and budgeting for a class party. The unit is intended to take about 10.5 hours of teaching and learning time spread over some months. It consists of nine student activities supported by teacher notes on curriculum, pedagogy and assessment. Student activities include ...

### The difference bar: generate hard 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 44. In most of these examples, the difference is greater than ten. Split the numbers into parts that are easy to work with, work out each part and then solve the original ...

### MoneySmart: The house of needs and wants

This is a unit of work integrating aspects of the mathematics, English and science curriculums around planning a school breakfast. The unit was written for year 3 and is intended to take about 12 hours. It consists of 11 student activities supported by teacher notes on curriculum, pedagogy and assessment. Student activities ...

### 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 ...

### 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 ...

### The difference bar: make your own hard 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 27 and 86. Choose your own pairs of numbers. Split the numbers into parts that are easy to work with, work out each part and then solve the original calculation. This learning ...

### Sushi monster - iTunes app

The Sushi monster needs to be fed the correct sum or product. Choose to play the addition or multipliaction game. In the addition game select the two numbers that make the target sum. In the multipication game select two numbers to make the target product. This game has several levels. Free when reviewed on 12/5/2015.

### Exploring number patterns

Find an addition or subtraction pattern relating to four numbers on a grid. Predict the next three numbers in the pattern. For example, predict the next three numbers in the following sequence: 60, 53, 46, 39...

### Pobble arrays: find two factors

Help creatures to line up and walk through gates in equal rows and columns. Look at the given number of pobbles, and enter the number of gates and rows. For example, predict how many equal rows of pobbles are needed to fit 12 of them through four gates. This learning object is one in a series of three objects.

### Squirt: two containers

Examine the relationships between capacities of various containers. Look at two containers that may have different diameters, heights and shapes. Fill a container and squirt liquids between the containers to establish the proportional relationship. Express relationships using mathematical notation such as a=6xb. This learning ...

### The difference bar: go figure

This tutorial is suitable for use with a screen reader. It explains how to split up numbers in your head when finding the difference between two numbers such as 26 and 73. Work through sample questions and instructions explaining how to use linear partitioning techniques. Find the difference between pairs of numbers. Split ...

### Squirt: two containers: level 2

Examine the relationships between capacities of containers of different shapes and sizes. Squirt liquids between two containers to establish the proportional relationship. Express relationships using mathematical notation such as a=6xb. This learning object is the second in a series of five objects that progressively increase ...

### Squirt: two containers: level 1

Examine the relationships between capacities of containers of the same shape, but different size. Squirt liquids between two containers to establish the proportional relationship. Express relationships using mathematical notation such as a=6xb. This learning object is the first in a series of five objects that progressively ...

### Pobble arrays: find a factor

Help creatures to line up and walk through gates in equal rows and columns. Look at the given numbers of pobbles and gates, and enter the number of rows. For example, predict how many equal rows of pobbles are needed to fit 12 of them through four gates. Check your prediction. This learning object is one in a series of ...

### Thinking addition: 2-digit plus 1-digit: assessment

Test your ability to turn a word problem into a 2-digit plus 1-digit equation. Solve the equation without a calculator. For example, use a partitioning tool to help solve the sum 15+8. Choose which strategy you used to solve the problem. View and print a report of your results. This assessment object is the first in a series ...

### Wishball: hundreds

Test your understanding of place value with three-digit numbers. Start with a three-digit whole number such as 507. A spinner provides a randomly generated digit. Choose its place value and add it to (or subtract it from) your starting number. Work towards a given target number, say 539, using other digits. You can choose ...

### Wishball challenge: hundreds

Challenge your understanding of place value in whole numbers up to 999. Receive a starting number, such as 328, and work towards turning it into a target number, such as 177, within 20 turns. Spin a random digit, choose its decimal place value and use the given operation (either addition or subtraction) on your starting ...