Addition & Subtraction

Learning Experiences

Addition & Subtraction

OUTCOME

A student:

MA1-5NA: uses a range of strategies and informal recording methods for addition and subtraction involving one- and two-digit numbers

TEACHING POINT | The word ‘difference’ has a specific meaning in this context, referring to the numeric value of the group. In everyday language, it can refer to any attribute. Students need to understand that the requirement to carry out subtraction can be indicated by a variety of language structures. The language used in the ‘comparison’ type of subtraction is quite different from that used in the ‘take away’ type. Students need to understand the different uses for the = sign, eg 4 + 1 = 5, where the = sign indicates that the right side of the number sentence contains ‘the answer’ and should be read to mean ‘equals’, compared to a statement of equality such as 4 + 1 = 3 + 2, where the = sign should be read to mean ‘is the same as’. |

LANGUAGE | Students should be able to communicate using the following language: counting on, counting back, combine, plus, add, take away, minus, the difference between, total, more than, less than, double, equals, is equal to, is the same as, number sentence, strategy. |

Represent and solve simple addition and subtraction problems using a range of strategies, including counting on, partitioning and rearranging parts | use the terms ‘add’, ‘plus’, ‘equals’, ‘is equal to’, ‘take away’, ‘minus’ and the ‘difference between’ |

use concrete materials to model addition and subtraction problems involving one- and two-digit numbers | |

use concrete materials and a number line to model and determine the difference between two numbers, eg | |

recognise and use the symbols for plus (+), minus (–) and equals (=) | |

record number sentences in a variety of ways using drawings, words, numerals and mathematical symbols | |

recognise, recall and record combinations of two numbers that add to 10 | |

create, record and recognise combinations of two numbers that add to numbers up to and including 9 | |

model and record patterns for individual numbers by making all possible whole-number combinations, eg 5+0=5 4+1=5 3+2=5 2+3=5 1+4=5 0+5=5 (Communicating, Problem Solving) | |

describe combinations for numbers using words such as ‘more’, ‘less’ and ‘double’, eg describe 5 as ‘one more than four’, ‘three combined with two’, ‘double two and one more’ and ‘one less than six’ (Communicating, Problem Solving) | |

create, record and recognise combinations of two numbers that add to numbers from 11 up to and including 20 | |

use combinations for numbers up to 10 to assist with combinations for numbers beyond 10 (Problem Solving) | |

investigate and generalise the effect of adding zero to a number, eg ‘Adding zero to a number does not change the number’ | |

use concrete materials to model the commutative property for addition and apply it to aid the recall of addition facts, eg 4 + 5 = 5 + 4 | |

relate addition and subtraction facts for numbers to at least 20, eg 5 + 3 = 8, so 8 – 3 = 5 and 8 – 5 = 3 | |

use and record a range of mental strategies to solve addition and subtraction problems involving one- and two-digit numbers, including: | |

counting on from the larger number to find the total of two numbers | |

counting back from a number to find the number remaining | |

counting on or back to find the difference between two numbers | |

using doubles and near doubles, eg 5 + 7: double 5 and add 2 | |

combining numbers that add to 10, eg 4 + 7 + 8 + 6 + 3: first combine 4 and 6, and 7 and 3, then add 8 | |

bridging to 10, eg 17 + 5: 17 and 3 is 20, then add 2 more | |

using place value to partition numbers, eg 25 + 8: 25 is 20 + 5, so 25 + 8 is 20 + 5 + 8, which is 20 + 13 | |

choose and apply efficient strategies for addition and subtraction (Problem Solving) | |

use the equals sign to record equivalent number sentences involving addition, and to mean ‘is the same as’, rather than as an indication to perform an operation, eg 5 + 2 = 3 + 4 | |

check given number sentences to determine if they are true or false and explain why, eg ‘Is 7 + 5 = 8 + 4 true? Why or why not?’ (Communicating, Reasoning) |

Learning Experiences

To be added