Reflection: Student Feedback Partitioning Segments in the Coordinate Plane - Section 3: Developing the Partitioning Formula


After teaching this lesson the first time, it became very clear that many students did not understand how to determine which partial fraction to apply to which endpoint's coordinates. Over and over again I would get questions like "How do you know which one is 2/5 and which one is 3/5?" For students who were accustomed to memorizing a formula, this was throwing them for a loop because their was some initial analysis and checking of conditions that needed to happen before applying the formula. In essence, there were actually two formulas: one for when the partitioning point is closer to the first endpoint, and another for when the partitioning point is closer to the second endpoint.

After getting this type of question so many times in tutoring and after class and seeing the light bulb turn on for students after I took them through the reasoning step by step, it made me realize that I should incorporate this type of scaffolded step-by-step reasoning within the lesson. That's what led me to create the "Reasoning" portion of the handout on page 2.

I suspect that next time I teach the lesson and require students to take their time going through this reasoning portion, it will lead to a far greater number of students being able to decide which fraction goes where, and why.

  How my students let me know what they need
  Student Feedback: How my students let me know what they need
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Partitioning Segments in the Coordinate Plane

Unit 9: Analytic Geometry
Lesson 6 of 7

Objective: SWBAT determine the coordinates of a point that partitions a line segment into segments of a given ratio.

Big Idea: 'Howdy Partishner'...In this lesson, students will use analytic geometry to define the coordinates of partitioning points.

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