Lesson plan

4. Apply length invariance to a real life scenario (A)

teaches Common Core State Standards CCSS.Math.Content.3.MD.B.4 http://corestandards.org/Math/Content/3/MD/B/4
teaches Common Core State Standards CCSS.Math.Content.3.NF.A.2 http://corestandards.org/Math/Content/3/NF/A/2
teaches Common Core State Standards CCSS.Math.Practice.MP5 http://corestandards.org/Math/Practice/MP5
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Lesson objective: Relate fractional invariance to a real life scenario.

This lesson provides an opportunity for students to apply their knowledge and understanding of the invariance of fractions to a mathematical situation. Students are asked to find start, end points, or total distance run along a ruler partitioned into different denominators.

Key Concept students will use: 

  • the quantitative measurement object is invariant (a toothpick's length does not change, regardless of how we align it to a ruler; the weight of a book doesn't change if we put another object on the scale with it)

Skills students will use:

  • unit fractions result from partitioning a whole; (Grade 3, Unit 4; 3.NF.A.1, 2a)

  • non-unit fractions are made up of unit fractions with the same denominator; (Grade 3, Unit 4; NF.A.1, 2a)

Students engage in Mathematical Practice 5 (use appropriate tools strategically) as they partition and align number lines and rulers in order to measure fractional lengths.

Key vocabulary: 

  • eighth
  • fourth
  • half
  • number line
  • partition
  • ruler