standard_description: Add and subtract within 1000, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method. Understand that in adding or subtracting three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, ones and ones; and sometimes it is necessary to compose or decompose tens or hundreds.
problem_activity: Narrative
This Number Talk encourages students to look for and make use of the structure of numbers in base-ten to mentally solve division problems. The reasoning elicited here will be helpful later in the lesson when students divide large numbers using increasingly more abstract strategies.
Launch
Groups of 2
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.
\(90 \div 3\)
\(96 \div 3\)
\(960 \div 3\)
\(954 \div 3\)
Student Response
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Activity Synthesis
“How did each expression help you find the next one?”
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?”


aligns: no