AC9M4A01 Year 4 Mathematics

Content descriptor find unknown values in numerical equations involving addition and subtraction, using the properties of numbers and operations

Elaborations

• • Elaboration 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
• • Elaboration 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
• • Elaboration 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
• • Elaboration 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