options: Extend the counting sequence.

Use place value understanding and properties of operations to perform multi-digit arithmetic. (A range of algorithms may be used.)

Generalize place value understanding for multi-digit whole numbers.
Grade 4 expectations in this domain are limited to whole numbers less than or equal to 1,000,000.

Work with numbers 11–19 to gain foundations for place value.

Use place value understanding and properties of operations to perform multi-digit arithmetic.
Grade 4 expectations in this domain are limited to whole numbers less than or equal to 1,000,000.

Understand place value.

Use place value understanding and properties of operations to add and subtract.

Perform operations with multi-digit whole numbers and with decimals to hundredths.

Understand the place value system.
problem_activity: Narrative
This Number Talk encourages students to look for and make use of structure to mentally evaluate a series of subtraction expressions. The numbers preview some benchmark angle measurements students will see in upcoming lessons.
Launch
Display one expression.
“Give me a signal when you have an answer and can explain how you got it.”
1 minute: quiet think time
Activity
Record answers and strategy.
Keep expressions and work displayed.
Repeat with each expression.
Student Facing
Find the value of each expression mentally.
\(90 - 45\)
\(270 - 45\)
\(270 - 135\)
\(360 - 135\)
Student Response
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Activity Synthesis
“What do these expressions have in common?” (The first number in each sequence is a multiple of 90.)
“How did this observation—that the first numbers are all multiples of 90—help you find the value of the differences?”
Consider asking:
“Who can restate _____’s reasoning in a different way?”
“Did anyone have the same strategy but would explain it differently?”
“Did anyone approach the expression in a different way?”
“Does anyone want to add on to _____’s strategy?”


correct_option_index: 4