Commutative Multiplication
Understand and apply the commutative property of multiplication and recognise that division is not commutative
What a learner can do afterwards
- Explain that 3 × 5 = 5 × 3 and show this with an array rotated
- Use commutativity to choose the easier calculation
- Demonstrate that 12 ÷ 3 ≠ 3 ÷ 12
The lesson
When you multiply two numbers, you can switch the order and the answer stays the same. 3 × 5 and 5 × 3 both equal 15.
Mia has 4 bags with 7 stickers in each bag. That is 4 × 7 = 28 stickers. If she had 7 bags with 4 stickers each instead, that is 7 × 4 = 28 too. Same total, just arranged differently.
If one order is easier to picture, use that one. 2 × 9 and 9 × 2 both equal 18, so pick whichever is simpler for you.
Division does not work this way. 12 ÷ 3 = 4, but 3 ÷ 12 is not 4. Switching a division around gives a different answer.
Multiplication gives the same answer both ways around, but division does not.
Watch it
Where it sits
This opens up
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.