Standard Algorithm: One-digit and Multi-digit Numbers, with Composing
10 min
Narrative
The purpose of this Number Talk is to highlight the calculations that students will make when they use the standard algorithm. The first three calculations are partial products. The fourth calculation is the sum of the first three, and this is the number that is recorded when performing the standard multiplication algorithm, to which students will be introduced in this lesson.
Launch
Display the first expression.
“Give me a signal when you have an answer and can explain how you got it.”
1 minute: quiet think time
Teacher Instructions
Record answers and strategies.
Keep problems and work displayed.
Repeat with each problem.
Student Task
Find the value of each product mentally.
3×3
3×20
3×600
3×623
Sample Response
9: I just knew it.
60: It's 6 tens.
1,800: It's 18 hundreds.
1,869: I added the previous three products.
Activity Synthesis (Teacher Notes)
“How is the last product related to the first three?” (It is the sum of the first three.)
“Did the first three calculations help you find the last product?” (Yes, I was able to add them together to find 3×623.)
Standards
Building On
4.NBT.5·Multiply a whole number of up to four digits by a one-digit whole number, and multiply two two-digit numbers, using strategies based on place value and the properties of operations. Illustrate and explain the calculation by using equations, rectangular arrays, and/or area models.
4.NBT.B.5·Multiply a whole number of up to four digits by a one-digit whole number, and multiply two two-digit numbers, using strategies based on place value and the properties of operations. Illustrate and explain the calculation by using equations, rectangular arrays, and/or area models.
Building Toward
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.
20 min
15 min
Knowledge Components
All skills for this lesson
No KCs tagged for this lesson
Standard Algorithm: One-digit and Multi-digit Numbers, with Composing
10 min
Narrative
The purpose of this Number Talk is to highlight the calculations that students will make when they use the standard algorithm. The first three calculations are partial products. The fourth calculation is the sum of the first three, and this is the number that is recorded when performing the standard multiplication algorithm, to which students will be introduced in this lesson.
Launch
Display the first expression.
“Give me a signal when you have an answer and can explain how you got it.”
1 minute: quiet think time
Teacher Instructions
Record answers and strategies.
Keep problems and work displayed.
Repeat with each problem.
Student Task
Find the value of each product mentally.
3×3
3×20
3×600
3×623
Sample Response
9: I just knew it.
60: It's 6 tens.
1,800: It's 18 hundreds.
1,869: I added the previous three products.
Activity Synthesis (Teacher Notes)
“How is the last product related to the first three?” (It is the sum of the first three.)
“Did the first three calculations help you find the last product?” (Yes, I was able to add them together to find 3×623.)
Standards
Building On
4.NBT.5·Multiply a whole number of up to four digits by a one-digit whole number, and multiply two two-digit numbers, using strategies based on place value and the properties of operations. Illustrate and explain the calculation by using equations, rectangular arrays, and/or area models.
4.NBT.B.5·Multiply a whole number of up to four digits by a one-digit whole number, and multiply two two-digit numbers, using strategies based on place value and the properties of operations. Illustrate and explain the calculation by using equations, rectangular arrays, and/or area models.
Building Toward
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.