Metric Conversion and Division by Powers of 10

10 min

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 values 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
Teacher Instructions
  • Share and record answers and strategies.
  • Repeat with each equation.

Student Task

Decide if each statement is true or false. Be prepared to explain your reasoning.

  • 5÷1,000=0.055 \div 1,000 = 0.05
  • 36÷100=0.3636 \div 100 = 0.36
  • 1,328÷1,000=1.3281,328 \div 1,000 = 1.328

Sample Response

  • False: 5 divided by 1,000 is 51,000\frac{5}{1,000} or 0.005.
  • True: 36 divided by 10 is 3.6 and 3.6 divided by 10 is 0.36.
  • True: There is 1 group of 1,000 and then 328 thousandths.
Activity Synthesis (Teacher Notes)
  • “How did you find the value of 1,328÷1,0001,328 \div 1,000?” (I thought of it as 1,328 thousandths and then wrote that as a decimal.)
Standards
Addressing
  • 5.NBT.2·Explain patterns in the number of zeros of the product when multiplying a number by powers of 10, and explain patterns in the placement of the decimal point when a decimal is multiplied or divided by a power of 10. Use whole-number exponents to denote powers of 10.
  • 5.NBT.A.2·Explain patterns in the number of zeros of the product when multiplying a number by powers of 10, and explain patterns in the placement of the decimal point when a decimal is multiplied or divided by a power of 10. Use whole-number exponents to denote powers of 10.

15 min

15 min