YEAR 5 MATHS FOCUS
NUMBERS AND ALGEBRA
ADDITION & SUBTRACTION
OUTCOME
A student:
MA35NA:
selects and applies appropriate strategies for addition and subtraction with counting numbers of any size
STRATEGIES  Written strategies using informal mental strategies (empty number line):
The difference can be shifted one unit to the left on an empty number line, so that 8000 − 673 becomes 7999 − 672, which is an easier subtraction to calculate. 
Written strategies using a formal algorithm (decomposition method):

TEACHING POINTS  In Stage 3, mental strategies need to be continually reinforced. 
Students may find recording (writing out) informal mental strategies to be more efficient than using formal written algorithms, particularly in the case of subtraction. 
LANGUAGE  Students should be able to communicate using the following language: plus, sum, add, addition, increase, minus, the difference between, subtract, subtraction, decrease, equals, is equal to, empty number line, strategy, digit, estimate, round to, budget. 
Teachers should model and use a variety of expressions for the operations of addition and subtraction, and should draw students’ attention to the fact that the words used for subtraction may require the operation to be performed with the numbers in the reverse order to that in which they are stated in the question. For example, ‘9 take away 3’ and ‘reduce 9 by 3’ require the operation to be performed with the numbers in the same order as they are presented in the question (ie 9 – 3). However, ‘take 9 from 3’, ‘subtract 9 from 3’ and ‘9 less than 3’ require the operation to be performed with the numbers in the reverse order to that in which they are stated in the question (i.e. 3 – 9). 
Expectations of Attainment
Use efficient mental and written strategies and apply appropriate digital technologies to solve problems (ACMNA291)  use the term ‘sum’ to describe the result of adding two or more numbers, eg ‘The sum of 7 and 5 is 12’ {Literacy} 
add three or more numbers with different numbers of digits, with and without the use of digital technologies, eg 42 000 + 5123 + 246  
select and apply efficient mental, written and calculator strategies to solve addition and subtraction word problems, including problems involving money {Literacy, Information and communication technology capability, Critical and creative thinking}  
– interpret the words ‘increase’ and ‘decrease’ in addition and subtraction word problems, eg ‘If a computer costs $1599 and its price is then decreased by $250, how much do I pay?’ {Communicating, Problem Solving, Literacy}  
record the strategy used to solve addition and subtraction word problems  
– use empty number lines to record mental strategies {Communicating, Problem Solving}  
– use selected words to describe each step of the solution process {Communicating, Problem Solving, Literacy}  
check solutions to problems, including by using the inverse operation {Critical and creative thinking} 
Use estimation and rounding to check the reasonableness of answers to calculations (ACMNA099)  round numbers appropriately when obtaining estimates to numerical calculations 
use estimation to check the reasonableness of answers to addition and subtraction calculations, e.g. 1438 + 129 is about 1440 + 130 {Critical and creative thinking} 
Create simple financial plans (ACMNA106)  use knowledge of addition and subtraction facts to create a financial plan, such as a budget, eg organise a class celebration on a budget of $60 for all expenses {Personal and social capability, Work and enterprise} 
– record numerical data in a simple spreadsheet {Communicating, Information and communication technology capability}  
– give reasons for selecting, prioritising and deleting items when creating a budget {Communicating, Reasoning, Critical and creative thinking, Personal and social capability, Work and enterprise} 
To be added