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  This lesson provided by:  
Author:Tonia Bevelle
System: Tuscaloosa City
School: Tuscaloosa City Board Of Education

  General Lesson Information  
Lesson Plan ID: 33167


What you know about the Bermuda Triangle?


The basis of this lesson is for students to form a connection between the importance of geometry as it relates to the Bermuda Triangle.  Students should think about the geographical locations and how they form a particular type of triangle.  Within the triangle exists a relationship between the angles and the length of the sides.  As the students reflect prior concepts and skills should come to mind to help them solve the problem. The ideas presented here can be used as the final lesson in a unit on triangles to summarize all that students have learned. Alternatively, the main problem from this lesson could be used as a final assessment activity for a unit on triangles.

This is a College- and Career-Ready Standards showcase lesson plan.

 Associated Standards and Objectives 
Content Standard(s):
MA2015 (9-12) Geometry
10. Prove theorems about triangles. Theorems include measures of interior angles of a triangle sum to 180o, base angles of isosceles triangles are congruent, the segment joining midpoints of two sides of a triangle is parallel to the third side and half the length, and the medians of a triangle meet at a point. [G-CO10]
MA2015 (9-12) Geometry
33. Use coordinates to compute perimeters of polygons and areas of triangles and rectangles, e.g., using the distance formula.* [G-GPE7]

Local/National Standards:

  • Standard 1: Make sense of problems and persevere in solving them
  • Standard 2: Reason abstractly and quantitatively
  • Standard 3: Construct viable arguments and critique the reasoning of others
  • Standard 4: Model with mathematics
  • Standard 5: Use appropriate tools strategically
  • Standard 6: Attend to precision
  • Standard 7: Look for and make use of structure
  • Standard 8: Look for and express regularity in repeated reasoning

Primary Learning Objective(s):

Students will:

  • Identify points in the plane that, when connected to the endpoints of a given segment, form a specific type of triangle
  • Classify triangles according to sides (scalene, isosceles, equilateral)
  • Classify triangles according to angles (right, acute, obtuse)

Additional Learning Objective(s):

  1. The students can then locate the three vertices of the Bermuda Triangle. (Miami, Puerto Rico, and Bermuda)
  2. Using a coordinate plane with the x and y axis, the students create points for each geographical location and find the distance between the three vertices of the triangle.
  3. This will help with defining the perimeter of the triangle.

 Preparation Information 

Total Duration:

31 to 60 Minutes

Materials and Resources:

1. Rulers

2. Pencil and Paper

3. Reference materials (i.e. books, Internet) about the Bermuda Triangle

4. Protractor

Technology Resources Needed:

Computer and Internet Connection



Prior to teaching this lesson, the teacher should view the videos. Print one copy of the worksheet and the answer key.  Make sure you get all necessary materials and have them at each station.



To begin the class, ask students the following questions:

  • How can you classify triangles according to their angles? [right, acute, obtuse]
  • How can you classify triangles according to their sides? [equilateral, isosceles, scalene]
  • What do you know about the Bermuda Triangle?


1.  After the introduction, allow the students to watch the video. Use the handout? What you know about the Bermuda Triangle?

2.  You can assign groups for this activity to allow the students to turn and talk and then answer questions. Make sure students record answers on the worksheet.


1.  After a brief discussion, distribute the Bermuda Triangle Sides and Angles activity sheet to all students. Answer any questions that students have regarding the activity.

2.  Once all questions have been answered and students are ready, allow them to work for 3-5 minutes individually to measure and classify angles. In addition, students need to measure the length of the sides.  (You will not need much time for this. During the discussion about types of triangles, prompt students to think about how sides and angles are related.

3.  For the next 3‑5 minutes, allow students to share their thoughts with a partner. During these discussions, students will often realize any errors that they made. 

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Assessment Strategies

Collect the student work on this problem and use it to determine each student’s level of understanding. 

Once the sides and angles are measured correctly, they should be able to classify the triangle as acute, scalene, right, or equilateral.


Ask the students the following questions:

1.  Knowing the lengths of the sides of the triangle, what is the perimeter?

2. How can you find the area of the Triangle?


Students can watch videos to review prerequisite skills such as measuring angles, sides, etc...Provide a powerpoint, video, and practice on classifying triangles by sides and angles.


PowerPoint: (Measuring, calculating, and drawing angles)


Each area below is a direct link to general teaching strategies/classroom accommodations for students with identified learning and/or behavior problems such as: reading or math performance below grade level; test or classroom assignments/quizzes at a failing level; failure to complete assignments independently; difficulty with short-term memory, abstract concepts, staying on task, or following directions; poor peer interaction or temper tantrums, and other learning or behavior problems.

Presentation of Material Environment
Time Demands Materials
Attention Using Groups and Peers
Assisting the Reluctant Starter Dealing with Inappropriate Behavior

Be sure to check the student's IEP for specific accommodations.
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