What Is a Thousandth?

10 min

Narrative

The purpose of this Estimation Exploration is to invite students to think about small fractions of a quantity in context. The mosaic pictured here is made up of many small square tiles. Square tiles are arranged in a complex pattern and are not identical in size but students can relate the denominator of a fraction giving the size of each tile, relative to the whole mosaic, to the total number of tiles making the mosaic. This helps them think of a fraction with a large denominator which prepares them to think about the fraction 11,000\frac{1}{1,000} in this lesson. 

Launch

  • Groups of 2
  • Display the image.
  • “What is an estimate that’s too high? Too low? About right?”
  • 1 minute: quiet think time
Teacher Instructions
  • “Discuss your thinking with your partner.”
  • 2–3 minutes: partner discussion
  • Share and record responses.

Student Task

What fraction of the whole image is 1 single square tile?

Record an estimate that is:

too low about right too high

Sample Response

Sample responses:

  • too low: 110,000\frac{1}{10,000} or less
  • about right: 13,000\frac{1}{3,000} to 1500\frac{1}{500}
  • too high: 1100\frac{1}{100} or more
Activity Synthesis (Teacher Notes)
  • “How did you make your estimate?” (I tried to estimate how many tiles made the whole picture and then used that as my denominator.)
  • “We will be investigating very small numbers and how to represent them in the next several lessons.”
Standards
Addressing
  • 5.NBT.A·Understand the place value system.
  • 5.NBT.A·Understand the place value system.

20 min

15 min