standard_description: Apply properties of operations as strategies to add and subtract. (Students need not use formal terms for these properties.) Examples: If 8 + 3 = 11 is known, then 3 + 8 = 11 is also known. (Commutative property of addition.) To add 2 + 6 + 4, the second two numbers can be added to make a ten, so 2 + 6 + 4 = 2 + 10 = 12. (Associative property of addition.)
problem_activity: Task
Decide if the equations are true or false. Explain your answer.
4 x 5 = 20
34 = 7 x 5
3 x 6 = 9 x 2
5 x 8 = 10 x 4
6 x 9 = 5 x 10
2 x (3 x 4) = 8 x 3
8 x 6 = 7 x 6 + 6
4 x (10 + 2) = 40 + 2


aligns: no