AC9M3A01 Year 3 Mathematics

Content descriptor recognise and explain the connection between addition and subtraction as inverse operations, apply to partition numbers and find unknown values in number sentences

Elaborations

• • Elaboration partitioning numbers using materials, part-part-whole diagrams or bar models, and recording addition and subtraction facts for each representation, explaining how each fact is connected to the materials, diagrams or models; for example, 16 + 8 = 24, 24\space – \space8 = 16, 8 = 24 \space–\space 16
• • Elaboration using the inverse relationship between addition and subtraction to find unknown values with a calculator; for example, representing the problem, “Peter had some money and then spent \$375, now he has \$158 left. How much did Peter have to start with?” as \square – \$375 = \$158 and solving the problem using \$375 + \$158 = \$533; solving 27 + \square = 63 using subtraction, \square = 63\space – \space27 or by counting on; 27, 37, 47, 57, 60, 63, so add 3 tens and 6 ones, so \square = 36
• • Elaboration exploring First Nations Australians’ stories and dances that show the connection between addition and subtraction, representing this as a number sentence and discussing how this conveys important information about balance in processes on Country/Place