Prove It (Part 1)

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Students will be able to develop and prove hyptheses about angles in triangles, in preparation for the next lesson, in which they will develop a proof of the Pythagorean theorem.

Big Idea

Students work on proving hypotheses – and end up proving the Pythagorean Theorem.

Introductory Problem

10 minutes
ProveItPart1_IntroProblemNarrative.docx page 1

Proving Hypotheses

30 minutes
ProveItPart1_ProvingHypothesesNarrative.docx page 1
ProveItPart1_ProvingHypothesesNarrative.docx page 2


5 minutes

With about five minutes to go, I ask the students to stop working and I let them know that I’d like each group to report out on their progress with the Parallel Lines problem

  1. I ask to hear first from any groups who are not yet finished:
    • What is their hypothesis?
    • Where are they in the problem solving process? 
    • Are they having any particular issues? If so, with what? 
  2. From groups who have finished, I ask for one observation from each group:
    • Did they struggle with anything in particular?
    • What did they find challenging? 
    • Did they find these tasks difficult or easy, and why?