The purpose of this Warm-up is to elicit the idea that 3 groups of 40 can also be seen as 12 groups of 10, which will be useful when students multiply one-digit whole numbers by multiples of 10 in a later activity. While students may notice and wonder many things, seeing that the total can be decomposed into rows of 30 and further decomposed into units of 10 are the important discussion points.
Launch
Groups of 2
Display the image.
“What do you notice? What do you wonder?”
1 minute: quiet think time
Teacher Instructions
“Discuss your thinking with your partner.”
1 minute: partner discussion
Share and record responses.
Student Task
What do you notice? What do you wonder?
Solution Steps (3)
1
Identify the structure of base-ten blocks
→4 rows × 3 columns of tens (each block = 10)
2
Count total tens
→4 × 3 = 12 tens
3
Find total value
→12 × 10 = 120 squares
Sample Response
Students may notice:
These are diagrams of base-ten blocks.
There are 10 squares (or ones) in each rectangle or block.
There are 4 rows and 3 columns of tens.
There are 3 tens in each row.
There are 30 in each row.
I could skip-count by 30 to find the total.
There are 12 groups of ten.
Students may wonder:
How many squares (or ones) are in each section?
How many squares are in each row?
How many squares are there in all?
Activity Synthesis (Teacher Notes)
“What is the value the diagram represents?” (120)
“How could noticing groups of tens help us find the total number of squares?” (There are 3 groups of 4 tens, which is 12 tens. There are 4 groups of 30, which is 12 tens. We could count by tens to find the total. We know 12 tens would be 120.)
Record equations that reflect student thinking, such as 3×4×10=12×10 and 4×30=12×10.
Standards
Addressing
3.NBT.3·Multiply one-digit whole numbers by multiples of 10 in the range 10—90 (e.g., 9 × 80, 5 × 60) using strategies based on place value and properties of operations.
3.NBT.A.3·Multiply one-digit whole numbers by multiples of 10 in the range 10–90 (e.g., <span class="math">\(9 \times 80\)</span>, <span class="math">\(5 \times 60\)</span>) using strategies based on place value and properties of operations.
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Multiply Multiples of 10
10 min
Narrative
The purpose of this Warm-up is to elicit the idea that 3 groups of 40 can also be seen as 12 groups of 10, which will be useful when students multiply one-digit whole numbers by multiples of 10 in a later activity. While students may notice and wonder many things, seeing that the total can be decomposed into rows of 30 and further decomposed into units of 10 are the important discussion points.
Launch
Groups of 2
Display the image.
“What do you notice? What do you wonder?”
1 minute: quiet think time
Teacher Instructions
“Discuss your thinking with your partner.”
1 minute: partner discussion
Share and record responses.
Student Task
What do you notice? What do you wonder?
Solution Steps (3)
1
Identify the structure of base-ten blocks
→4 rows × 3 columns of tens (each block = 10)
2
Count total tens
→4 × 3 = 12 tens
3
Find total value
→12 × 10 = 120 squares
Sample Response
Students may notice:
These are diagrams of base-ten blocks.
There are 10 squares (or ones) in each rectangle or block.
There are 4 rows and 3 columns of tens.
There are 3 tens in each row.
There are 30 in each row.
I could skip-count by 30 to find the total.
There are 12 groups of ten.
Students may wonder:
How many squares (or ones) are in each section?
How many squares are in each row?
How many squares are there in all?
Activity Synthesis (Teacher Notes)
“What is the value the diagram represents?” (120)
“How could noticing groups of tens help us find the total number of squares?” (There are 3 groups of 4 tens, which is 12 tens. There are 4 groups of 30, which is 12 tens. We could count by tens to find the total. We know 12 tens would be 120.)
Record equations that reflect student thinking, such as 3×4×10=12×10 and 4×30=12×10.
Standards
Addressing
3.NBT.3·Multiply one-digit whole numbers by multiples of 10 in the range 10—90 (e.g., 9 × 80, 5 × 60) using strategies based on place value and properties of operations.
3.NBT.A.3·Multiply one-digit whole numbers by multiples of 10 in the range 10–90 (e.g., <span class="math">\(9 \times 80\)</span>, <span class="math">\(5 \times 60\)</span>) using strategies based on place value and properties of operations.
