standard_description: Apply properties of operations as strategies to multiply and divide. (Students need not use formal terms for these properties.) ^( )Examples: If 6 × 4 = 24 is known, then 4 × 6 = 24 is also known. (Commutative property of multiplication.) 3 × 5 × 2 can be found by 3 × 5 = 15, then 15 × 2 = 30, or by 5 × 2 = 10, then 3 × 10 = 30. (Associative property of multiplication.) Knowing that 8 × 5 = 40 and 8 × 2 = 16, one can find 8 × 7 as 8 × (5 + 2) = (8 × 5) + (8 × 2) = 40 + 16 = 56. (Distributive property.)
problem_activity: Narrative
The purpose of this warm-up is to for students to discuss how much space a ton of garbage takes up, which will be useful when students consider 3,300 tons of plastic trash in shipping containers in a later activity. Some students may not know the precise definition of a ton. Encourage students to visualize what 2,000 pounds of trash might look like. The synthesis gives students an opportunity to consider the kind and the amount of trash produced in their community.
Launch
Groups of 2
Display the image.
“What do you notice? What do you wonder?”
1 minute: quiet think time
Activity
“Discuss your thinking with your partner.”
1 minute: partner discussion
Share and record responses.
Student Facing
What do you notice? What do you wonder?
[IMG]
Student Response
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Activity Synthesis
“The average garbage truck can hold 12–14 tons of garbage.”
If needed, “1 ton is the same as 2,000 pounds.”
“If this truck collects trash only from our school (or neighborhood) what kinds of things might the truck be filled with?”
“How long do you think it would take our school (or neighborhood ) to completely fill the truck?”


aligns: no