standard_description: Mentally add 10 or 100 to a given number 100–900, and mentally subtract 10 or 100 from a given number 100–900.
problem_activity: Narrative
The purpose of this True or False is to elicit strategies and understandings students have for working with the value of the digits in a three-digit number. These understandings help students consider place value when comparing three-digit numbers. This will be helpful later when students compare three-digit numbers without visual representations.
Launch
Display one statement.
“Give me a signal when you know whether the statement is true and can explain how you know.”
1 minute: quiet think time
Activity
Share and record answers and strategy.
Repeat with each statement.
Student Facing
Decide if each statement is true or false. Be prepared to explain your reasoning.
\(86 > 80 + 4\)
\(400 + 40 + 6 < 846\)
\(330 < 300 + 3\)
\(500 + 50 > 505\)
Student Response
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Activity Synthesis
“How could expanded form help you decide whether the expression
\(330 < 300 + 3\)
is true or false?” (I knew that 30 is 3 tens and 3 is only 3 ones, so 330 is greater than 303.)


aligns: no