Find the Greatest Product
10 min
Narrative
The purpose of this Warm-up is for students to discuss the location of digits in products, which will be useful when students try to find the greatest product in a later activity. While students may notice and wonder many things, the locations of the digits 6, 4, 1, and 8 is the important discussion point.
Launch
- Groups of 2
- Display the image.
Teacher Instructions
- “What do you notice? What do you wonder?”
- 1 minute: quiet think time
- 1 minute: partner discussion
- Share and record responses.
Student Task
What do you notice? What do you wonder?
Sample Response
Students may notice:
- Both products have the same digits, but some of the digits are in different places.
- Both products have factors with the number 41 in them.
- The 8 and the 6 switch places.
- What are the values of the products?
- Are they equal?
- Which one is greater?
Activity Synthesis (Teacher Notes)
- “Without finding the values, which product do you think will be greater? Explain your reasoning.” (I think 841×6 will be greater because 841 is a lot more than 641. I think 641×8 will be greater because both products are 4,800 plus some 41s. 641×8 has more 41s than 841×6.)
- “We are going to revisit these problems in the Lesson Synthesis.”
Standards
Addressing
- 5.NBT.5·Fluently multiply multi-digit whole numbers using the standard algorithm.
- 5.NBT.B.5·Fluently multiply multi-digit whole numbers using the standard algorithm.
15 min
20 min
Knowledge Components
All skills for this lesson
No KCs tagged for this lesson
Find the Greatest Product
10 min
Narrative
The purpose of this Warm-up is for students to discuss the location of digits in products, which will be useful when students try to find the greatest product in a later activity. While students may notice and wonder many things, the locations of the digits 6, 4, 1, and 8 is the important discussion point.
Launch
- Groups of 2
- Display the image.
Teacher Instructions
- “What do you notice? What do you wonder?”
- 1 minute: quiet think time
- 1 minute: partner discussion
- Share and record responses.
Student Task
What do you notice? What do you wonder?
Sample Response
Students may notice:
- Both products have the same digits, but some of the digits are in different places.
- Both products have factors with the number 41 in them.
- The 8 and the 6 switch places.
- What are the values of the products?
- Are they equal?
- Which one is greater?
Activity Synthesis (Teacher Notes)
- “Without finding the values, which product do you think will be greater? Explain your reasoning.” (I think 841×6 will be greater because 841 is a lot more than 641. I think 641×8 will be greater because both products are 4,800 plus some 41s. 641×8 has more 41s than 841×6.)
- “We are going to revisit these problems in the Lesson Synthesis.”
Standards
Addressing
- 5.NBT.5·Fluently multiply multi-digit whole numbers using the standard algorithm.
- 5.NBT.B.5·Fluently multiply multi-digit whole numbers using the standard algorithm.