Compare Decimals

10 min

Narrative

The purpose of this Warm-up is for students to compare different ways of representing a decimal number. It will be important in this and future lessons to write a given decimal in a different form. For example, it is convenient to write 7.3 as 7.300 in order to compare it to 7.299. 

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
Teacher Instructions
  • Share and record answers and strategy.
  • Repeat with each statement.

Student Task

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

  • 7.06=7.0067.06 = 7.006
  • 7.06=7.0607.06 = 7.060
  • 7.06=7.6007.06 = 7.600

Sample Response

  • False: They both have 7 but 6 hundredths is not the same as 6 thousandths.
  • True: They both have 7 and 6 hundredths. One number also shows 0 thousandths but that does not change the value.
  • False: One is 7 and 6 tenths while the other is 7 and 6 hundredths.
Activity Synthesis (Teacher Notes)
  • “How did you decide if the second equation is true?” (I looked at the value of the digits in each place. They are all the same except for an extra 0. But 0 thousandths does not change the value of the number.)
Standards
Addressing
  • 5.NBT.3·Read, write, and compare decimals to thousandths.
  • 5.NBT.A.3·Read, write, and compare decimals to thousandths.

10 min

20 min