The purpose of this Number Talk is to elicit strategies and understandings students have for adding within 1,000 and to help students develop fluency. When students consider the addends carefully and adjust them to facilitate addition (such as by subtracting from one and adding to the other), they practice looking for and making use of structure (MP7).
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 expressions and work displayed.
Repeat with each expression.
Student Task
Find the value of each expression mentally.
306+199
318+297
275+325
275+329
Sample Response
505: I took 1 away from 506 and added it to 199 to make 200. 305+200=505
615: I took 3 from 318 to make 315 and added the 3 to 297 to make 300. 315+300=615
600: 200 plus 300 is 500 and 75 plus 25 is another 100.
604: It’s 4 more than the previous expression.
Activity Synthesis (Teacher Notes)
“How do you decide how much to add to one addend and take away from the other addend?”
Standards
Addressing
3.NBT.2·Fluently add and subtract within 1000 using strategies and algorithms based on place value, properties of operations, and/or the relationship between addition and subtraction.
3.NBT.A.2·Fluently add and subtract within 1000 using strategies and algorithms based on place value, properties of operations, and/or the relationship between addition and subtraction.
20 min
15 min
Knowledge Components
All skills for this lesson
No KCs tagged for this lesson
What Makes Sense in the Problem?
10 min
Narrative
The purpose of this Number Talk is to elicit strategies and understandings students have for adding within 1,000 and to help students develop fluency. When students consider the addends carefully and adjust them to facilitate addition (such as by subtracting from one and adding to the other), they practice looking for and making use of structure (MP7).
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 expressions and work displayed.
Repeat with each expression.
Student Task
Find the value of each expression mentally.
306+199
318+297
275+325
275+329
Sample Response
505: I took 1 away from 506 and added it to 199 to make 200. 305+200=505
615: I took 3 from 318 to make 315 and added the 3 to 297 to make 300. 315+300=615
600: 200 plus 300 is 500 and 75 plus 25 is another 100.
604: It’s 4 more than the previous expression.
Activity Synthesis (Teacher Notes)
“How do you decide how much to add to one addend and take away from the other addend?”
Standards
Addressing
3.NBT.2·Fluently add and subtract within 1000 using strategies and algorithms based on place value, properties of operations, and/or the relationship between addition and subtraction.
3.NBT.A.2·Fluently add and subtract within 1000 using strategies and algorithms based on place value, properties of operations, and/or the relationship between addition and subtraction.