standard_description: Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
problem_activity: Narrative
The purpose of this True or False is for students to demonstrate the strategies and understandings they have for dividing by powers of 10. In this lesson they will convert from a smaller metric unit to a larger unit which means dividing by an appropriate power of 10. The problems here are selected so that students can begin to see how the value of the digits in a number change when that number is divided by 100 or 1,000.
Launch
Display one equation.
“Give me a signal when you know whether the equation is true and can explain how you know.”
1 minute: quiet think time
Activity
Share and record answers and strategy.
Repeat with each equation.
Student Facing
Decide if each statement is true or false. Be prepared to explain your reasoning.
\(5 \div 1,\!000 = 0.05\)
\(36 \div 100 = 0.36\)
\(1,\!328 \div 1,\!000 = 1.328\)
Student Response
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Activity Synthesis
“How did you find the value of
\(1,\!328 \div 1,\!000\)
?” (I thought of it as 1,328 thousandths and then wrote that as a decimal.)


aligns: no