## Reflection: Developing a Conceptual Understanding Time for Triangles - Section 3: Exploration #2 and Proof of Triangle Sum Theorem

In this lesson, I found that my students really struggled to identify the concepts of a side of a triangle being a transversal (cutting through 2 parallel lines).  When I drew in the parallel lines and transversal, I extended these lines, similar to Time for Triangles example so that students could see more clearly the relationship between the lines and angles. I think this really helped my students to understand how to prove that the sum of the interior angles in a triangle is 180 degrees.

Developing a Conceptual Understanding: Using Transversal and Parallel Lines

# Time for Triangles

Unit 4: Tremendous Triangles
Lesson 1 of 10

## Big Idea: Students will measure, cut and measure again to learn and prove key properties of triangles

Print Lesson
3 teachers like this lesson
Standards:
Subject(s):
85 minutes

### Stephanie Conklin

##### Similar Lessons

###### Applying Triangle Congruence
Geometry » Triangles and Congruence
Big Idea: Students learn how proving triangles congruent can be used as part of a larger strategy in a proof.
Favorites(4)
Resources(18)
Ault, CO
Environment: Rural

###### Prove It (Part 1)
Geometry » Similar and Right Triangles
Big Idea: Students work on proving hypotheses – and end up proving the Pythagorean Theorem.
Favorites(1)
Resources(11)
Amsterdam, NY
Environment: Urban

###### Relationships between Angles and Sides of a Triangle
Geometry » Proofs about Triangles
Big Idea: This lesson gives students the opportunity to discover the relationship between the sides and angles of a triangle through a hands-on activity.
Favorites(0)
Resources(16)
New York, NY
Environment: Urban