Reflection: Developing a Conceptual Understanding Triangle Inequality Theorem - Section 2: Explore


This discovery activity really allows kids to write the rules for determining the possible side lengths of a triangle themselves. I walked the kids through one of the colors (red) so that they understood my expectations, but then I set them free to finish the table and answer the four questions - I have included a short video clip of the kids in action: Discovery Activity Clip. Today the kids did a great job of generating the answers for the reflective questions - see the Class Notes and Student Work for more. 

The discovery activity was a great segway into the notes, and the discussion on how to set the parameters for a third side.  I was hoping they would be able to set the parameters on their own, but they struggled a bit - so I gave them 6 choices of a third side and asked that they talk at their tables about which of my options could be possibilities.  Then I was able to get them thinking about what x had to be between, and from there they were able to figure out how to set up the inequality for the possible third side length.

  Developing a Conceptual Understanding: Discovery Reflection
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Triangle Inequality Theorem

Unit 7: Geometric Figures
Lesson 9 of 14

Objective: Students will be able to determine if three side lengths can form a triangle.

Big Idea: Any three sides lengths can't form a triangle? NOPE! Students will use straws of various lengths to investigate this theorem.

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